Gettysburg Basin Archipelago – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

August 20, 2024August 24, 2024

Heat Flux Processes in Streams and Their Impact on Coldwater and Coolwater Fishes

The deluge of rain that soaked the lower Susquehanna watershed during last week is now just a memory. Streams to the west of the river, where the flooding courtesy of the remnants of Hurricane Debby was most severe, have reached their crest and receded. Sliding away toward the Chesapeake and Atlantic is all that runoff, laden with a brew of pollutants including but not limited to: agricultural nutrients, sediment, petroleum products, sewage, lawn chemicals, tires, dog poop, and all that litter—paper, plastics, glass, Styrofoam, and more. For aquatic organisms including our freshwater fish, these floods, particularly when they occur in summer, can compound the effects of the numerous stressors that already limit their ability to live, thrive, and reproduce.

One of those preexisting stressors, high water temperature, can be either intensified or relieved by summertime precipitation. Runoff from forested or other densely vegetated ground normally has little impact on stream temperature. But segments of waterways receiving significant volumes of runoff from areas of sun-exposed impervious ground will usually see increases during at least the early stages of a rain event. Fortunately, projects implemented to address the negative impacts of stormwater flow and stream impairment can often have the additional benefit of helping to attenuate sudden rises in stream temperature.

Stream Subjected to Agricultural Runoff — While a row of trees along a creek can help provide protection from the thermal impact of the sun, a vegetative riparian buffer must be much wider to be effective for absorbing, cooling, and treating runoff from fields, lawns, and paved surfaces. This buffer is too narrow to prevent surface runoff from polluting the water.

Of the fishes inhabiting the Lower Susquehanna River Watershed’s temperate streams, the least tolerant of summer warming are the trouts and sculpins—species often described as “coldwater fishes”. Coldwater fishes require water temperatures below 70° Fahrenheit to thrive and reproduce. The optimal temperature range is 50° to 65° F. In the lower Susquehanna valley, few streams are able to sustain trouts and sculpins through the summer months—largely due to the effects of warm stormwater runoff and other forms of impairment.

Sculpins, including the Blue Ridge Sculpin (Cottus caeruleomentum) seen here, are native coldwater fishes which, during the 11,000 years since the last glacial maximum, have had the availability of their favored habitat sharply reduced by warming water temperatures and a rising Atlantic. During this interval, seawater has inundated the path of the “Late” Pleistocene lower Susquehanna which passed through the section of flooded river watershed we now call Chesapeake Bay and continued across the continental shelf to what was, during the glacial maximum, the river’s mouth at Norfolk Canyon. Today, cut off from neighboring drainage basins, sculpins survive exclusively in cold headwaters, and only in those where human alterations including pollution, dams, channelization, and reduced base flow haven’t yet eliminated their isolated populations. Formerly believed to be composed of two widespread North American species, the Slimy Sculpin (Cottus cognatus) and the Mottled Sculpin (Cottus bairdii), study in recent decades is discovering that sculpin populations in the present-day lower Susquehanna and neighboring Potomac headwaters consist of at least three newly delineated species: Blue Ridge Sculpin, Potomac Sculpin (Cottus gerardi), and Checkered Sculpin (Cottus sp.), the latter an as yet undescribed species found only in the refugium of limestone springs in the Potomac drainage in West Virginia; Frederick and Washington Counties, Maryland; and Franklin County, Pennsylvania. (United States Geological Survey image)

Ice Age Susquehanna — Stare at this for a little while, you’ll figure it out…………More than 11,000 years ago, during the last glacial maximum, when sea level was about 275 feet lower than it is today, there was no Chesapeake Bay, just a great Susquehanna River that flowed to the edge of the continental shelf and its mouth at Norfolk Canyon. It was a river draining taiga forests of pine, spruce , and fir, and it carried along the waters of all the present-day bay’s tributaries and more. The section of the river’s watershed we presently call the lower Susquehanna was, at the time, the upper Susquehanna watershed. Brook Trout and sculpins had the run of the river and its tributaries back then. And the entire watershed was a coldwater fishery, with limestone and other groundwater springs providing not refuge from summer heat, but a place to escape freezing water. (United States Geological Survey base image)

Norfolk Canyon, the mouth of the Susquehanna River during the most recent glacial maximum, now lies more than 275 feet below the surface of the ocean and plunges to more than a mile in depth along the finger of out wash from the gorge. (United States Geological Survey image)

Rainbow. Brown, and Brook Trout — Tens of thousands of trout are raised in state-operated and cooperative nurseries for stocking throughout the lower Susquehanna valley. These rearing facilities are located on spring-fed headwaters with sufficient flow to assure cold temperatures year round. While the Rainbow Trout and Brown Trout (Salmo trutta) are the most commonly stocked species, the Brook Trout (Salvelinus fontinalis) is the only one native to American waters. It is the least tolerant of stream warming and still reproduces in the wild only in a few pristine headwaters streams in the region. During spring, all three of these species have been observed on rare occasions entering the fish lift facilities at the hydroelectric dams on the river, presumably returning to the Susquehanna as sea-run trout.

Coldwater fishes are generally found in small spring-fed creeks and headwaters runs. Where stream gradient, substrate, dissolved oxygen, and other parameters are favorable, some species may be tolerant of water warmer than the optimal values. In other words, these temperature classifications are not set in stone and nobody ever explained ichthyology to a fish, so there are exceptions. The Brown Trout for example is sometimes listed as a “coldwater transition fish”, able to survive and reproduce in waters where stream quality is exceptionally good but the temperature may periodically reach the mid-seventies.

The Eastern Blacknose Dace is sometimes classified as a “coldwater transition fish”. It can be found in headwaters runs as well as in creeks with good water quality.

The Longnose Dace is another “coldwater transition fish” known only from clear, clean, flowing waters.

More tolerant of summer heat than the trouts, sculpins, and daces are the “coolwater fishes”—species able to feed, grow, and reproduce in streams with a temperature of less than 80° F, but higher than 60° F. Coolwater fishes thrive in creeks and rivers that hover in the 65° to 70° F range during summer.

Creek Chubs — The Creek Chub is a familiar species of “coolwater fish” seldom found remaining in waters exceeding 80 degrees Fahrenheit.

The Yellow Perch (Perca flavescens) was perhaps the most frequently targeted coolwater “gamefish” in the Lower Susquehanna River Watershed prior to the introduction of the Northern Pike (Esox lucius) and Muskellunge (Esox masquinongy). Today’s prevalence of warmwater streams and the dozens of species of non-native predatory fishes now naturalized within them have left the Yellow Perch populations greatly reduced and all but forgotten by anglers. Out of sight, out of mind. (National Park Service image)

What are the causes of modern-day reductions in coldwater and coolwater fish habitats in the lower Susquehanna River and its hundreds of miles of tributaries? To answer that, let’s take a look at the atmospheric, cosmic, and hydrologic processes that impact water temperature. Technically, these processes could be measured as heat flux—the rate of heat energy transfer per unit area per unit time, frequently expressed as watts per meter squared (W/m²). Without getting too technical, we’ll just take a look at the practical impact these processes have on stream temperatures.

HEAT FLUX PROCESSES IN A SEGMENT OF STREAM

Heat Flux Processes on Streams and Rivers — Heat Flux Processes on Stream and River Segments. These processes could be measured as heat flux—the rate of heat energy transfer per unit area per unit time. (Environmental Protection Agency image)

- - INCOMING TEMPERATURE AND FLOW—The baseline temperature of stream water entering a given segment of waterway is obviously the chief factor determining its temperature when exiting that segment. Incoming temperature and flow also determine the water’s susceptibility to heat absorption or loss while transiting the segment. Lower flows may subject the given volume of water to a greater loss or gain of heat energy during the time needed to pass through the segment than the same volume at a higher flow. Lower flows may also reduce stream velocity and extend a given volume of water’s exposure time to the exchange of heat energy while moving through the segment. Generally speaking…
    1. …the higher the stream flow, the less a given volume of that stream’s water may be impacted by the effects of the heat flux processes within the segment.
    2. …the lower the stream flow, the more a given volume of that stream’s water may be impacted by the effects of the heat flux processes within that segment.
    3. …the temperature and flow rate of precipitation entering the segment are factors that determine the impact of its heat energy transfer to or from a given volume of the stream’s waters.
    4. …the temperature and flow rate of runoff and point-source discharges entering the segment are factors that determine the impact of their heat energy transfer to or from a given volume of the stream’s waters.

Stormwater Discharge into Channelized Creek — Stormwater from impervious surfaces including roads, parking lots, roofs, and lawns quickly impacts temperatures in small creeks. Channelized streams are availed few of the positive attributes provided by many of the heat flux processes we’re about to see. They therefore suffer from severe impairment and are exposed to temperature extremes that few aquatic organisms can survive. Runoff from sun-heated pavement during a summer thunderstorm can often exceed 100 degrees Fahrenheit and can, at sufficient flow rate, quickly raise the temperature of a small stream to well over 90 degrees.

Stormwater Runoff — Stormwater runoff not only poses a thermal threat to waterways, its a significant source of a wide variety of pollutants.

- - GROUNDWATER INPUT—In streams connected to the aquifer, the temperature in a flowing segment can be impacted by the influx of cold groundwater. With temperatures ranging from about 52° to 60° Fahrenheit, groundwater will absorb heat from the stream in summer, and warm it in the winter. In warmwater streams, coldwater and coolwater fishes will often seek areas of the substrate where groundwater is entering for use as refugium from the summer heat. Yellow Perch in the lower Susquehanna are known to exhibit this behavior.

Gaining Stream — Creeks and rivers connected to the aquifer and receiving supplemental flow from it are known as “gaining streams”. These streams frequently feed water into the aquifer as well. (United States Geological Survey image)

Losing Stream — When flowing through an area experiencing drought or an excessive removal of groundwater (lots of wells, etc.), a waterway can become a “losing stream”, one that surrenders a portion of its flow to recharge the aquifer. Further downstream, the reduced flow can make such a creek or river more susceptible to the effects of heat flux processes. (United States Geological Survey image)

Disconnected Stream — Seriously depleted aquifers can lead to a “disconnected stream”. Smaller waterways subjected to these conditions will sometimes lose all their flow to the ground, often causing a catastrophic failure of the aquatic ecosystem supported therein. (United States Geological Survey image)

Urban Flooding and Dry Streambed — Urban runoff overwhelms this small stream with polluted water than can reach temperatures of 100 degrees or more (left), then lets it high and dry with no baseflow during periods of dry weather (right) as the waterway becomes disconnected from the much-depleted aquifer.

Stormwater Retention Basin — Well-designed and properly constructed stormwater retention basins not only recharge groundwater supplies for wells and streams, they can also help prevent thermal pollution in waterways. Planted with native wetland species and allowed to thrive, they can become treasured wildlife islands in otherwise inhospitable environs. The benefits don’t stop there; plants also help sequester nutrients contained in the runoff.

- - HYPORHEIC EXCHANGE—Related to groundwater input, hyporheic exchange is the slow movement of water through the rock, sand, gravel, and soils composing the streambed, saturated shoreline, shallow aquifer, and connected floodplain of a creek or river. As a heat flux process, hyporheic exchange helps moderate extremes in seasonal water temperatures by conducting energy between the solid materials in the zone and the flowing water. Hyporheic zones are important habitats for many species of aquatic invertebrates and spawning fish. Natural chemical processes within these zones convert ammonia-producing wastes into nitrite, then nitrate, allowing it to be absorbed as food by plants growing in the stream or in the alluvium within the zone. Vegetation removal, channelization, legacy sediments, silt deposits, and man-made walls and dams can negate the benefits of hyporheic exchange.

Hyporheic Exchange — Exchange of surface and ground water within the hyporheic zone is most directly associated with high-gradient (left) and meandering (right) segments of streams. (United States Geological Survey image)

Legacy Sediments and Fill — Very common on streams in the lower Susquehanna valley are these accumulations of legacy sediments at the sites of former mill ponds. After the dams were removed, the creeks began eroding their way down through the mire as they tried to reestablish their floodplains and find their native substrate. These trapped waterways are not only cut off from their hyporheic zones, they’re now a major source of nutrient and sediment pollution. Misguided landowners like this one frequently dump fill into these sites to “save their land” and “control flooding”. The fill and materials added to “shore up the banks” do nothing to fix what ails the creek, but instead displace more water to make the impact of flooding even more widespread.

Flooplain and Stream Restoration — Rehabilitation projects that remove legacy sediments help restore hyporheic exchange by reconnecting the stream to its underlying geology, its floodplain, and its wetlands. Rising waters remain in the floodplain where they get a good bio-scrubbing and help replenish the creek and groundwater supply. As the experts say, “floodplains are for flooding.”

- - ATMOSPHERIC EXCHANGE (CONVECTION, EVAPORATION)—Primarily a process by which a stream loses heat energy and cools its waters, atmospheric exchange is also a means by which a warm air mass can relinquish heat to cooler waters and thus increase their temperature. This phenomenon can be dramatically enhanced when a stream passes through a so-called urban heat island where air temperatures remain warm through the night. Convection, the movement of heat energy through a fluid (liquid or gas), causes warmer, less-dense water to rise to the surface of a stream, particularly where there is minimal turbulence. When the air above is cooler than the water’s surface layer, the stream will conduct heat energy across the water/atmosphere interface causing the warmed air molecules to rise in a convection column. If the atmospheric relative humidity is less than 100%, some surface water will vaporize—a process that expends more of the stream’s heat energy. The rate of convective and evaporative cooling in a given stream segment is directly related to the degree of difference between the water temperature and air temperature, and to the relative humidity in the air mass above the lake, creek, or river. The mechanical action of stream turbulence including rapids, riffles, and falls increases the contact area between air and water to maximize the atmospheric exchange of heat energy. The convective air current we call surface wind has a turbulent wave-producing effect on water that can also maximize atmospheric exchange; think of a cold autumn wind robbing heat energy from a warm lake or river or a hot summer wind imparting its heat to a cooler creek. These exchanges are both conductive in nature (air-to-water/water-to-air) and evaporative, the latter being expedited by the movement of dry air over warm water.

Usually classified as one of the coolwater fishes, the bottom-dwelling Tessellated Darter can thrive in the warmer creeks and in the main stem of the Susquehanna by inhabiting riffles where atmospheric exchange in the form of increased evaporation helps reduce temperatures and convective currents carry the cooler, well-oxygenated water to the streambed.

Three mile Island Unit 1 Cooling Towers — Humans utilize the concept of atmospheric exchange, adopting the phenomena of evaporation and convection to cool the hot waters produced during electric generation and other industrial processes before discharge into a lake or river.

- - STREAMBED CONDUCTIVE EXCHANGE—In the lower Susquehanna watershed, there may be no better natural example of streambed conductive exchange than the Triassic-Jurassic diabase pothole bedrocks of Conewago Falls on the river at the south end of Three Mile Island.

During sunny days, the massive diabase pothole rocks at Conewago Falls absorb solar (shortwave) radiation, then conduct that heat energy into the flowing water, often continuing to pass the accumulated warmth into the river during the night. On cloudy days, the riverbed collects longwave atmospheric radiation, a heat flux process that yields significantly less energy for conduction into the rapids, riffles, and pools of the falls. During periods of low river flow, the heating effect of streambed conductive exchange can become magnified. Compared to conditions that prevail when torrents of turbid water are rushing through the falls, partially exposed bedrock surrounded by clear water collects radiated energy much more efficiently, then conducts the heat to a greatly reduced volume of passing water. During summer and autumn, this process can create a mix of temperature zones within the falls with warmer water lingering in slow-moving pools and cooler water flowing in the deeper fast-moving channels. Along the falls’ mile-long course, a haven is created for aquatic organisms including warmwater and some coolwater fishes, oft times attracting anglers and a variety of hungry migrating birds as well.

Classified as one of our coolwater fishes, the Fallfish finds favorable conditions for feeding, growing, and spawning in the well-oxygenated waters of Conewago Falls.

Though the lower Susquehanna River is classified as a warmwater fishery, the Northern Hog Sucker (Hypentelium nigricans), another of our native coolwater fishes, finds the fast-moving waters of Conewago Falls to its liking. Northern Hog Suckers are known to inhabit streams cold enough to host trout. They exhibit remarkable home range fidelity, sometimes spending their entire lives occupying the same several hundred feet of waterway. Northern Hog Suckers are often designated an indicator of good water quality, intolerant of many stream impairment parameters. Their presence in Conewago Falls provides testament to the quality of the warmwater fishery there.

Severely Impaired Channelized Stream — An unnatural example. The reduced base flow in this channelized and severely impaired creek has been rendered vulnerable to the negative impacts of several heat flux processes including streambed conductive exchange. Urban stormwater/surfacewater inflow, solar (shortwave) radiation, and heat conducted into the stream from the masonry walls, curbs, and raceway can all conspire to cook aquatic organisms with life-quenching summer water temperatures exceeding 90 degrees Fahrenheit.

- - SOLAR (SHORTWAVE) RADIATION—The sun provides the energy that fuels the earth’s complex climate. The primary heat flux process that heats our planet is the absorption of solar radiation in the shortwave spectrum, which includes ultraviolet, visible, and infrared frequencies at the upper end of the longwave spectrum. Streams and other bodies of water absorb the greatest amounts of solar (shortwave) radiation during the weeks around summer solstice when the sun at mid-day is closer to zenith than at any other time of the year. However, the heating impact of the radiation may be greatest when the volume of water in the creek, river, or lake is at its minimum for the year—often during early fall.

The Sun — The rate, measured in watts per square meter, at which solar (shortwave) energy is directly radiated to a given area on the earth’s surface (including streams and other waters) is determined by: solar activity, the angle of the sun in the sky, aspect (slope) of the receiving surface, the opacity of the overlying atmosphere, and the distance of the earth from the sun. The former varies with the year’s seasons, the time of day, and the latitude of a given area. The latter is currently at its annual minimum when earth is at perihelion during the early days of January, thus providing the northern hemisphere with a little bump in radiation during the shortest days of the year when the sun is at its lowest angle in the sky. (NASA image)

Solar (Shortwave) Radiation — A varying portion of the solar (shortwave) radiation reaching the earth is reflected back into space by clouds. A smaller share is absorbed by the atmosphere, thus heating it. An even lesser quantity is reflected back into space by water and land. The remainder of the energy is absorbed by the planet’s surfaces, its water and land. (NASA image)

- - INCIDENT SHORTWAVE RADIATION—Also known as insolation (incoming solar radiation), incident shortwave radiation is the sum total energy of both the direct solar radiation that travels to the earth’s surface unaffected by the atmosphere and the diffuse radiation, waves that have been weakened and scattered by constituents of the atmosphere before reaching the planet’s surface. On a cloudy day, the warming of terrestrial surfaces including streams and other bodies of water is the result of diffuse radiation. On days with any amount of sunshine at all, both direct and diffuse radiation heat our waters and lands.

Pumkinseed — Warmwater fishes such as the native Pumpkinseed (Lepomis gibbosus) thrive in sun-drenched 70-to-85-degree waters as long as other heat flux processes prevent sudden temperature increases and oxygen depletion.

Mowed Stream Bank — Mowed stream banks offer a waterway no protection from incoming solar (shortwave) radiation, nor terrestrial forms of impairment including nutrient-rich stormwater runoff and silt.

- - REFLECTED SHORTWAVE RADIATION—known as albedo, reflected solar (shortwave) radiation is energy directed away from the earth’s surface before being absorbed. A surface’s albedo value is basically determined by its color, black having little reflective value, white and silvery surfaces reflecting nearly all solar (shortwave) radiation away. A surface with no reflective properties has an albedo value of 0, while a totally reflective surface has a value of 1. Clean snow with a value of about 0.85 to 0.9 (85% to 90%) is a highly reflective surface; yellow snow isn’t as good. A stream, river, or lake blanketed with ice and snow will absorb very little solar energy and will rely upon other heat flux processes to trigger a melt and thaw. The surface of open water has a varying albedo value determined mostly by the angle of the sun. Solar radiation striking the water’s surface at a low angle is mostly reflected away, while that originating at an angle closer to zenith is more readily absorbed.

Forested Stream — To avoid the heating effects of solar (shortwave) and atmospheric longwave radiation, coldwater and coolwater fishes require streams offering protection from full exposure to direct sunlight and cloud cover. Runs and creeks flowing beneath a closed canopy of forest trees are shielded from 25% or more of incoming radiation and are thus able to better maintain thermal stability during the most vulnerable period of the year for temperature-sensitive fishes, May through October.

- - LONGWAVE RADIATION—Radiation in the longwave spectrum is composed of infrared waves at frequencies lower than those of the shortwave spectrum. Longwave radiation, sometimes just called infrared radiation, is produced by the earth and its atmosphere and is propagated in all directions, day and night. It warms mostly the lower atmosphere which in turn warms the earth’s surface including its waters. Some longwave energy can even be radiated into the waterway from its own streambed—and the stream can return the favor. Other forms of mass surrounding a stream such as a rocky shoreline or a man-made structure such as bridge pier can trade longwave radiation with a waterway. The effect of these latter exchanges is largely trivial and never rivals the heat flux transfer of warm to cold provided by conduction.

Longwave Radiation — Longwave radiation emissions slow as the temperature of the emitting mass decreases, just as they also increase with temperature of the mass. Longwave radiation emissions therefore decrease with altitude along with the temperature of the water vapor, carbon dioxide, methane, and other gases that produce them. As such, the highest reaches of the atmosphere have a greatly reduced capability of shedding longwave radiation into space. At ground level, lakes, creeks, and streams receive their greatest dose of longwave radiation while beneath the cover of low-lying clouds or fog. (NASA image)

- - CANOPY RADIATION—Trees emit longwave radiation that may have a limited heat flux impact on waterway temperature. This radiation is diffuse, of scattered effect, and scarcely detectable, particularly beneath multilayered dense canopies. Some of the infrared energy transmitted by the tree canopy is radiated skyward as well.
  - WATER RADIATION—Water, like all earthly matter composed of vibrating molecules, emits longwave radiation. This heat flux process provides an ongoing cooling effect to streams, rivers, lakes, and oceans—warmer ones shedding infrared energy at a faster rate than those that are cold.

Now that we have a basic understanding of the heat flux processes responsible for determining the water temperatures of our creeks and rivers, let’s venture a look at a few graphics from gauge stations on some of the lower Susquehanna’s tributaries equipped with appropriate United States Geological Survey monitoring devices. While the data from each of these stations is clearly noted to be provisional, it can still be used to generate comparative graphics showing basic trends in easy-to-monitor parameters like temperature and stream flow.

Each image is self-labeled and plots stream temperature in degrees Fahrenheit (bold blue) and stream discharge in cubic feet per second (thin blue).

West Conewago Creek 90 Days — The West Conewago Creek drains much of the Gettysburg Basin’s Triassic redbeds in Adams and northern York Counties in Pennsylvania and includes a small headwaters area in northern Maryland. The gauge station is located just a over a mile upstream from the waterway’s mouth on the Susquehanna just below Conewago Falls. Right through the summer heatwave, this 90-day graph shows a consistent daily pattern of daytime rises in temperature and nighttime cooling. To the right, a rapid cool down can be seen coinciding with two periods of high water, the first from a series of heavy thundershowers, the second from flooding caused by the remnants of Hurricane Debby. Notice that the early August downpours were so heavy that they cooled the hot surface runoff and waterway quickly, without creating a rise in stream temperature at the gauging station. Had this monitoring device been located on a small tributary in an area with an abundance of impervious surfaces, there would probably have been a brief rise in stream temperature prior to the cooldown. (United States Geological Survey image)

The daily oscillations in temperature reflect the influence of several heat flux processes. During the day, solar (shortwave) radiation and convection from summer air, especially those hot south winds, are largely responsible for the daily rises of about 5° F. Longwave radiation has a round-the-clock influence—adding heat to the stream during the day and mostly shedding it at night. Atmospheric exchange including evaporative cooling may help moderate the rise in stream temperatures during the day, and certainly plays a role in bringing them back down after sunset. Along its course this summer, the West Conewago Creek absorbed enough heat to render it a warmwater fishery in the area of the gauging station. The West Conewago is a shallow, low gradient stream over almost its entire course. Its waters move very slowly, thus extending their exposure time to radiated heat flux and reducing the benefit of cooling by atmospheric exchange. Fortunately for bass, catfish, and sunfish, these temperatures are in the ideal range for warmwater fishes to feed, grow, and reproduce—generally over 80° F, and ideally in the 70° to 85° F range. Coolwater fishes though, would not find this stream segment favorable. It was consistently above the 80° F maximum and the 60° to 70° F range preferred by these species. And coldwater fishes, well, they wouldn’t be caught dead in this stream segment. Wait, scratch that—the only way they would be caught in this segment is dead. No trouts or sculpins here.

The Codorus Creek drains primarily the carbonate valleys of York County to the south of the West Conewago watershed. This gauge station is located about a mile upstream from the creek’s mouth on the Susquehanna just below Haldeman Riffles. The graphic pattern is very similar to that of the West Conewago’s: daily heating and cooling cycles and a noticeable drop in stream temperature in early August caused by a day of thundershowers followed by the remnants of Hurricane Debby. (United States Geological Survey image)

Look closely and you’ll notice that although the temperature pattern on this chart closely resembles that of the West Conewago’s, the readings average about 5 degrees cooler. This may seem surprising when one realizes that the Codorus follows a channelized path through the heart of York City and its urbanized suburbs—a heat island of significance to a stream this size. Before that it passes through numerous impoundments where its waters are exposed to the full energy of the sun. The tempering factor for the Codorus is its baseflow. Despite draining a smaller watershed than its neighbor to the north, the Codorus’s baseflow (low flow between periods of rain) was 96 cubic feet per second on August 5th, nearly twice that of the West Conewago (51.1 cubic feet per second on August 5th). Thus, the incoming heat energy was distributed over a greater mass in the Codorus and had a reduced impact on its temperature. Though the Codorus is certainly a warmwater fishery in its lower reaches, coolwater and transitional fishes could probably inhabit its tributaries in segments located closer to groundwater sources without stress. Several streams in its upper reaches are in fact classified as trout-stocked fisheries.

This is a zoomed-in look at the previous graph showing the impact of a rainfall event on the water temperatures in Codorus Creek. Unlike the sharp declines accompanying the deluge of flood waters during the two events in early August, these lesser storms in late June generated just enough runoff to capture heat energy from impervious surfaces and warm the creek, temporarily breaking the daily heating/cooling cycle. Upstream in the immediate area of the runoff, the impact on the stream and/or its tributaries was probably much more dramatic, certainly raising temperatures into the nineties or above. (United States Geological Survey image)

Kreutz Creek drains a carbonate bedrock area of York County and flows parallel to the Lincoln Highway (US 30) to enter the Susquehanna at Wrightsville. The gauging station is about one mile upstream from the creek’s mouth. (United States Geological Survey image)

The Kreutz Creek gauge shows temperature patterns similar to those in the West Conewago and Codorus data sets, but notice the lower overall temperature trend and the flow. Kreutz Creek is a much smaller stream than the other two, with a flow averaging less than one tenth that of the West Conewago and about one twentieth of that in the Codorus. And most of the watershed is cropland or urban/suburban space. Yet, the stream remains below 80° F through most of the summer. The saving graces in Kreutz Creek are reduced exposure time and gradient. The waters of Kreutz Creek tumble their way through a small watershed to enter the Susquehanna within twenty-four hours, barely time to go through a single daily heating and cooling cycle. As a result, their is no chance for water to accumulate radiant and convective heat over multiple summer days. The daily oscillations in temperature are less amplified than we find in the previous streams—a swing of about three degrees compared to five. This indicates a better balance between heat flux processes that raise temperature and those that reduce it. Atmospheric exchange in the stream’s riffles, forest cover, and good hyporheic exchange along its course could all be tempering factors in Kreutz Creek. From a temperature perspective, Kreutz Creek provides suitable waters for coolwater fishes.

Muddy Creek drains portions of southern York County through rolling farmland and woodlots. There are no large impoundments or widespread urban impacts in the watershed, which may help explain its slightly lower temperature trends. (United States Geological Survey image)

Muddy Creek is a trout-stocked fishery, but it cannot sustain coldwater species through the summer heat. Though temperatures in Muddy Creek may be suitable for coolwater fishes, silt, nutrients, low dissolved oxygen, and other factors could easily render it strictly a warmwater fishery, inhabited by species tolerant of significant stream impairment.

Chiques Creek drains mostly limestone farmland in northwestern Lancaster County. The gauging station is located near the stream’s mouth on the Susquehanna at Chiques (Chickies) Rock. Oscillations in temperature again resemble the other waterways, but daily highs remain almost entirely below 80 degrees. (United States Geological Survey image)

A significant number of stream segments in the Chiques watershed have been rehabilitated to eliminate intrusion by grazing livestock, cropland runoff, and other sources of impairment. Through partnerships between a local group of watershed volunteers and landowners, one tributary, Donegal Creek, has seen riparian buffers, exclusion fencing, and other water quality and habitat improvements installed along nearly ever inch of its run from Donegal Springs through high-intensity farmland to its mouth on the main stem of the Chiques just above its confluence with the Susquehanna. The improved water quality parameters in the Donegal support native coldwater sculpins and an introduced population of reproducing Brown Trout. While coldwater habitat is limited to the Donegal, the main stem of the Chiques and its largest tributary, the Little Chiques Creek, both provide suitable temperatures for coolwater fishes.

Limestone Formation on Little Chiques Creek — Streams in the Chiques Creek and similar limestone watersheds often pass through areas with significant bedrock formations. Heat flux processes including groundwater input, hyporheic exchange, and streambed conductive exchange can have a greater influence on water temperature along these segments.

The Common Shiner (Luxilus cornutus), a fish tolerant of warmwater streams, prefers cool, clear waters for spawning. For protection from late-spring and summer heat, breeding males may seek a section of creek with a streambed inflow of limestone groundwater to defend as their nesting territory.

A closeup of the Chiques Creek graph showing what appears to be a little bump in temperature caused by surface runoff during a couple of late-May showers. Stream rehabilitation is an ongoing process and the pressures of land disturbances both old and new present challenges to those who make it their passion to fix the wrongs that have been inflicted upon our local waters. Even the exemplary Donegal Creek faces new threats from urbanization in one of its headwater areas several miles to the northwest of the historic springs. (United States Geological Survey image)

Conewago Creek (East) drains primarily Triassic redbed farmlands in Dauphin, Lancaster, and Lebanon Counties. Much of the headwaters area is forested but is experiencing an increasing rate of encroachment by housing and some commercial development. Conewago Creek (East) enters the Susquehanna on the east side of Conewago Falls at Three Mile Island. The watershed is equipped with three U.S.G.S. gauge stations capable of providing temperature data. This first one is located just over a mile upstream of the creek’s mouth. (United States Geological Survey image)

Despite its meander through and receipt of water from high-intensity farmland, the temperature of the lower Conewago (East) maxes out at about 85° F, making it ideal for warmwater fishes and even those species that are often considered coolwater transition fishes like introduced Smallmouth Bass, Rock Bass, Walleye, and native Margined Madtom. This survivable temperature is a testament to the naturally occurring and planted forest buffers along much of the stream’s course, particularly on its main stem. But the Conewago suffers serious baseflow problems compared to other streams we’ve looked at so far. Just prior to the early August storms, flow was well below 10 cubic feet per second for a drainage area of more than fifty square miles. While some of this reduced flow is the result of evaporation, much of it is anthropogenic in origin as the rate of groundwater removal continues to increase and a recent surge in stream withdraws for irrigation reaches its peak during the hottest days of summer.

Juvenile Rock Bass — A juvenile Rock Bass.

A closer look at the Conewago Creek (East) graphic shows the temperature drop associated with a series of thundershowers and the remnants of Hurricane Debby in early August. Despite the baseflow being below five cubic feet per second, the cooling effect of the downpours as measured in the area of the gauge was significant enough to overwhelm any heating of runoff that may have occurred as precipitation drained across hardened soils or man-made impervious surfaces. (United States Geological Survey image)

A little side note—the flow rate on the Conewago at the Falmouth gauge climbed to about 160 cubic feet per second as a result of the remnants of Hurricane Debby while the gauge on the West Conewago at Manchester skyrocketed to about 20,000 cubic feet per second. Although the West Conewago’s watershed (drainage area) is larger than that of the Conewago on the east shore, it’s larger only by a multiple of two or three, not 125. That’s a dramatic difference in rainfall!

The Bellaire monitoring station on Conewago Creek (East) is located on the stream’s main stem just downstream from the mouth of Little Conewago Creek, a tributary with its origins in farmland and woodlots. (United States Geological Survey image)

The temperatures at the Bellaire monitoring station, which is located upstream of the Conewago’s halfway point between its headwaters in Mount Gretna and its mouth, are quite comparable to those at the Falmouth gauge. Although a comparison between these two sets of data indicate a low net increase in heat absorption along the stream’s course between the two points, it also suggests sources of significant warming upstream in the areas between the Bellaire gauge and the headwaters.

Data from the gauge site on the Little Conewago Creek shows a temperature averaging about five degrees cooler than the gauge several miles downstream on the main stem of the Conewago at Bellaire. (United States Geological Survey image)

The waters of the Little Conewago are protected within planted riparian buffers and mature woodland along much of their course to the confluence with the Conewago’s main stem just upstream of Bellaire. This tributary certainly isn’t responsible for raising the temperature of the creek, but is instead probably helping to cool it with what little flow it has.

Juvenile Eastern Blacknose Dace (top) and a juvenile Longnose Dace. — A stream like the Little Conewago Creek with daily temperatures that remain mostly below 80 degrees and retreat to 75 degrees or less during the night can be suitable for coldwater transition fishes like these juvenile Eastern Blacknose Dace (top) and Longnose Dace.

Though mostly passing through natural and planted forest buffers above its confluence with the Little Conewago, the main stem’s critically low baseflow makes it particularly susceptible to heat flux processes that raise stream temperatures in segments within the two or three large agricultural properties where owners have opted not to participate in partnerships to rehabilitate the waterway. The headwaters area, while largely within Pennsylvania State Game Lands, is interspersed with growing residential communities where potable water is sourced from hundreds of private and community wells—every one of them removing groundwater and contributing to the diminishing baseflow of the creek. Some of that water is discharged into the stream after treatment at the two municipal sewer plants in the upper Conewago. This effluent can become quite warm during processing and may have significant thermal impact when the stream is at a reduced rate of flow. A sizeable headwaters lake is seasonally flooded for recreation in Mount Gretna. Such lakes can function as effective mid-day collectors of solar (shortwave) radiation that both warms the water and expedites atmospheric exchange.

Upper Conewago Creek (East) Watershed — The Conewago Creek (East) Watershed from the Bellaire U.S.G.S. Gauging Station (lower left) upstream to the headwaters in Mount Gretna. (United States Geological Survey image)

Though Conewago Creek (East) is classified as a trout-stocked fishery in its upper reaches in Lebanon County, its low baseflow and susceptibility to warming render it inhospitable to these coldwater fishes by late-spring/early summer.

Despite being considered a warmwater fish, the River Chub (Nocomis micropogon) will ascend streams like the Conewago to seek cooler, gravel-bottomed waters for spawning. Reduced baseflow has probably rendered the stream currently too small for this species on Pennsylvania State Game Lands in Colebrook where this specimen was photographed in 2018.

The Golden Shiner, another warmwater fish, often ascends streams to enter cooler water. Juvenile Golden Shiners like this one will move into shallower headwaters not only to seek reduced temperatures, but to escape large predatory fishes as well.

Irrigation using stream water. — Irrigation of agricultural fields using a large portion of the already diminished baseflow in the Conewago Creek (East) just downstream of the Bellaire gauging station. Despite millions of dollars in investment to rehabilitate this Susquehanna valley stream, the riparian buffers and other practices can have little effect when the creek gets sucked down to just a trickle. Low baseflow is a hard nut to crack. It’s best prevented, not corrected.

Hammer Creek, a trout-stocked fishery, originates, in part, within Triassic conglomerate in the Furnace Hills of Lebanon County, then flows north into the limestone Lebanon Valley where it picks up significant flow from other tributaries before working its way south back through the Furnace Hills into the limestone farmlands of Lancaster County. From there the stream merges with the Cocalico Creek, then the Conestoga River, and at last the Susquehanna. Note the tremendous daily temperature oscillations on this headwaters stream as it surges about 15 degrees each day before recovering back close to groundwater temperature by sunrise the next day. (United States Geological Survey image)

The removal of two water supply dams on the headwaters of Hammer Creek at Rexmont eliminated a large source of temperature fluctuation on the waterway, but did little to address the stream’s exposure to radiant and convective heat flux processes as it meanders largely unprotected out of the forest cover of Pennsylvania State Game Lands and through high-intensity farmlands in the Lebanon Valley. Moderating the temperature to a large degree is the influx of karst water from Buffalo Springs, located about two miles upstream from this gauging station, and other limestone springs that feed tributaries which enter the Hammer from the east and north. Despite the cold water, the impact of the stream’s nearly total exposure to radiative and other warming heat flux processes can readily be seen in the graphic. Though still a coldwater fishery by temperature standards, it is rather obvious that rapid heating and other forms of impairment await these waters as they continue flowing through segments with few best management practices in place for mitigating pollutants. By the time Hammer Creek passes back through the Furnace Hills and Pennsylvania State Game Lands, it is leaning toward classification as a coolwater fishery with significant accumulations of sediment and nutrients. But this creek has a lot going for it—mainly, sources of cold water. A core group of enthusiastic landowners could begin implementing the best management practices and undertaking the necessary water quality improvement projects that could turn this stream around and make it a coldwater treasure. An organized effort is currently underway to do just that. Visit Trout Unlimited’s Don Fritchey Chapter and Donegal Chapter to learn more. Better yet, join them as a volunteer or cooperating landowner!

Male Creek Chub — The male Creek Chub, one of our coolwater fishes, develops head tubercles and becomes flushed with color during spawning season. Hammer Creek not only provides a home for the Creek Chub, its cold headwaters provide refuge for a population of native Brook Trout too.

Like no other example we’ve looked at so far, this closeup of the Hammer Creek graphic shows temperature bumps correlating with the stormwater runoff from early August’s rains. Because the stream flow is small and the precipitation rate was not as great at this location, the effect of heat flux from runoff is more readily apparent. (United States Geological Survey image)

Brook Trout adult and juvenile. (United States Fish and Wildlife Service image by Ryan Hagerty)

For coldwater fishes, the thousands of years since the most recent glacial maximum have seen their range slowly contract from nearly the entirety of the once much larger Susquehanna watershed to the headwaters of only our most pristine streams. Through no fault of their own, they had the misfortune of bad timing—humans arrived and found coldwater streams and the groundwater that feeds them to their liking. Some of the later arrivals even built their houses right on top of the best-flowing springs. Today, populations of these fishes in the region we presently call the Lower Susquehanna River Watershed are seriously disconnected and the prospect for survival of these species here is not good. Stream rehabilitation, groundwater management, and better civil planning and land/water stewardship are the only way coldwater fishes, and very possibly coolwater fishes as well, will survive. For some streams like Hammer Creek, it’s not too late to make spectacular things happen. It mostly requires a cadre of citizens, local government, project specialists, and especially stakeholders to step up and be willing to remain focused upon project goals so that the many years of work required to turn a failing stream around can lead to success.

Riparian Buffer — Riparian buffers with fences to exclude livestock can immediately begin improving water quality. With establishment of such vegetative buffers, the effects of stressors that otherwise eliminate coldwater and coolwater fishes from these segments will begin to diminish.

You’re probably glad this look at heat flux processes in streams has at last come to an end. That’s good, because we’ve got a lot of work to do.

You Don't Have Time to Mow, We've Got Work to Do — Add one more benefit to the wildflower meadow, it infiltrates stormwater to recharge the aquifer much better than mowed grass. And another related plus, it reduces runoff and its thermal pollution. Besides, you don’t have time to mow grass, because we have work to do!

Our native coldwater fishes including the Potomac Sculpin will survive only if we protect and expand the scattered few habitats where they have taken refuge. They have no choice but to live in these seriously threatened places, but we do. So let’s give ’em some space. How ’bout it? (United States Fish and Wildlife Service image by Ryan Hagerty)

August 10, 2022August 13, 2022

Shakedown Cruise of the S. S. Haldeman

First there was the Nautilus. Then there was the Seaview. And who can forget the Yellow Submarine? Well, now there’s the S. S. Haldeman, and today we celebrated her shakedown cruise and maiden voyage. The Haldeman is powered by spent fuel that first saw light of day near Conewago Falls at a dismantled site that presently amounts to nothing more than an electrical substation. Though antique in appearance, the vessel discharges few emissions, provided there aren’t any burps or hiccups while underway. So, climb aboard as we take a cruise up the Susquehanna at periscope depth to have a quick look around!

Brunner Island as seen from the east channel.

Close-in approach to emergent Water Willow growing on an alluvial Island.

The approach to York Haven Dam and Conewago Falls from the west channel.

A pair of Powdered Dancers on a midriver log.

Watertight and working fine. Let’s flood the tanks and have a peek at the benthos. Dive, all dive!

American Eelgrass/Tapegrass — American Eelgrass, also known as Tapegrass, looks to be growing well in the channels. Historically, vast mats of this plant were the primary food source for the thousands of Canvasback ducks that once visited the lower Susquehanna each autumn.

As is Water Stargrass (Heteranthera dubia). When mature, both of these native plants provide excellent cover for young fish. Note the abundance of shells from deceased Asiatic Clams (Corbicula fluminea) covering the substrate.

Mayfly nymph — A three-tailed mayfly (Ephemeroptera) nymph and a several exoskeletons cling to the downstream side of a rock.

Comb-lipped Casemaker Caddisfly larva and case. — This hollowed-out stick may be a portable protective shelter belonging to a Comb-lipped Casemaker Caddisfly larva (Calamoceratidae). The larva itself appears to be extending from the end of the “case” in the upper right of the image. Heteroplectron americanum, a species known for such behavior, is a possibility.

In the Susquehanna and its tributaries, the Rusty Crayfish (Faxonius rusticus) is an introduced invasive species. It has little difficulty displacing native species due to its size and aggressiveness.

Freshwater Snails Susquehanna: Virginian River Horn Snail — Summers with conditions that promote eelgrass and stargrass growth tend to be big years for Virginian River Horn Snails (Elimia virginica). 2022 appears to be one of those years. They’re abundant and they’re everywhere on the rocks and gravel substrate in midriver. Feeding almost incessantly on algae and detritus, these snails are an essential component of the riverine ecosystem, breaking down organic matter for final decomposition by bacteria and fungi.

Susquehanna Snails: Virginian River Horn Snails and Lesser Mystery Snails — Virginian River Horn Snails with Lesser Mystery Snails (Campeloma decisum), another native species commonly encountered at Conewago Falls and in surrounding waters.

Freshwater Snails Susquehanna: River Snail and Virginian River Horn Snail — A River Snail (Leptoxis carinata), also known as a Crested Mudalia, hitching a ride on a Virginian River Horn Snail. The two species are frequently found together.

Mollusks of the Susquehanna: Yellow Lampmussel and River Snail — A River Snail cleaning the shell of a native freshwater Unionidae mussel, Lampsilis cariosa, commonly called the Yellow Lampmussel or Carried Lampmussel. Because of their general decline in abundance and range, all Unionidae mussels are protected in Pennsylvania.

Fishes of the Susquehanna: Banded Darter — The Banded Darter (Etheostoma zonale) is a member of the perch family (Percidae).

Fishes of the Susquehanna: Smallmouth Bass — A Smallmouth Bass in strong current.

Fishes of the Susquehanna: Spotfin or Satinfin Shiners — Along the edge of an alluvial island at midriver, Cyprinella (Spotfin or Satinfin) Shiners gather in the cover of an emergent stand of Water Willow. The closely related Spotfin Shiner (Cyprinella spiloptera) and Satinfin Shiner (Cyprinella analostanus) are nearly impossible to differentiate in the field.

Fishes of the Susquehanna: Spotfin or Satinfin Shiner — A breeding condition male Cyprinella (Spotfin or Satinfin) Shiner.

Fishes of the Susquehanna; Juvenile Channel Catfish — A juvenile Channel Catfish.

We’re finding that a sonar “pinger” isn’t very useful while running in shallow water. Instead, we should consider bringing along a set of Pings—for the more than a dozen golf balls seen on the river bottom. It appears they’ve been here for a while, having rolled in from the links upstream during the floods. Interestingly, several aquatic species were making use of them.

A golf ball used as an anchor point for silk cases woven by Net-spinning Caddisfly (Hydropsychidae) larvae to snare food from the water column.

Freshwater Snails (Gastropods) of the Lower Susquehanna River Watershed: Creeping Ancylid (Ferrissia species) — A Creeping Ancylid (Ferrissia species), a tiny gastropod also known as a Coolie Hat Snail, River Limpet, or Brook Freshwater Limpet, inhabits the dimple on a “Top Flight”.

We now know why your golf balls always end up in the drink, it’s where they go to have their young.

Well, it looks like the skipper’s tired and grumpy, so that’s all for now. Until next time, bon voyage!

June 24, 2022June 24, 2022

Three Mile Island and Agnes: Fifty Years Later

Fifty years ago this week, the remnants of Hurricane Agnes drifted north through the Susquehanna River basin as a tropical storm and saturated the entire watershed with wave after wave of torrential rains. The storm caused catastrophic flooding along the river’s main stem and along many major tributaries. The nuclear power station at Three Mile Island, then under construction, received its first major flood. Here are some photos taken during the climax of that flood on June 24, 1972. The river stage as measured just upstream of Three Mile Island at the Harrisburg gauge crested at 33.27 feet, more than 10 feet above flood stage and almost 30 feet higher than the stage at present. At Three Mile Island and Conewago Falls, the river was receiving additional flow from the raging Swatara Creek, which drains much of the anthracite coal region of eastern Schuylkill County—where rainfall from Agnes may have been the heaviest.

Three Mile Island flooding from Agnes 1972. — **1972-** From the river’s east shore at the mouth of Conewago Creek, Three Mile Island’s “south bridge” crosses the Susquehanna along the upstream edge of Conewago Falls. The flood crested just after covering the roadway on the span. Floating debris including trees, sections of buildings, steel drums, and rubbish began accumulating against the railings on the bridge’s upstream side, leading observers to speculate that the span would fail. When a very large fuel tank, thousands of gallons in capacity, was seen approaching, many thought it would be the straw that would break the camel’s back. It wasn’t, but the crashing sounds it made as it struck the bridge then turned and began rolling against the rails was unforgettable. (Larry L. Coble, Sr. image)

**2022-** Three Mile Island’s “south bridge” as it appeared this morning, June 24,2022.

**2022-** A modern view of the same location.

**2022-** Three Mile Island Unit 1 as it appears today: shut down, defueled, and in the process of deconstruction.

**2022-** A current look at T.M.I. Unit 2, shut down since the accident and partial meltdown in 1979.

Pictures capture just a portion of the experience of witnessing a massive flood. Sometimes the sounds and smells of the muddy torrents tell us more than photographs can show.

Aside from the booming noise of the fuel tank banging along the rails of the south bridge, there was the persistent roar of floodwaters, at the rate of hundreds of thousands of cubic feet per second, tumbling through Conewago Falls on the downstream side of the island. The sound of the rapids during a flood can at times carry for more than two miles. It’s a sound that has accompanied the thousands of floods that have shaped the falls and its unique diabase “pothole rocks” using abrasives that are suspended in silty waters after being eroded from rock formations in the hundreds of square miles of drainage basin upstream. This natural process, the weathering of rock and the deposition of the material closer to the coast, has been the prevailing geologic cycle in what we now call the Lower Susquehanna River Watershed since the end of the Triassic Period, more than two hundred million years ago.

More than the sights and sounds, it was the smell of the Agnes flood that warned witnesses of the dangers of the non-natural, man-made contamination—the pollution—in the waters then flowing down the Susquehanna.

Because they float, gasoline and other fuels leaked from flooded vehicles, storage tanks, and containers were most apparent. The odor of their vapors was widespread along not only along the main stem of the river, but along most of the tributaries that at any point along their course passed through human habitations.

Blended with the strong smell of petroleum was the stink of untreated excrement. Flooded treatment plants, collection systems overwhelmed by stormwater, and inundated septic systems all discharged raw sewage into the river and many of its tributaries. This untreated wastewater, combined with ammoniated manure and other farm runoff, gave a damaging nutrient shock to the river and Chesapeake Bay.

Adding to the repugnant aroma of the flood was a mix of chemicals, some percolated from storage sites along watercourses, and yet others leaking from steel drums seen floating in the river. During the decades following World War II, stacks and stacks of drums, some empty, some containing material that is very dangerous, were routinely stored in floodplains at businesses and industrial sites throughout the Susquehanna basin. Many were lifted up and washed away during the record-breaking Agnes flood. Still others were “allowed” to be carried away by the malicious pigs who see a flooding stream as an opportunity to “get rid of stuff”. Few of these drums were ever recovered, and hundreds were stranded along the shoreline and in the woods and wetlands of the floodplain below Conewago Falls. There, they rusted away during the next three decades, some leaking their contents into the surrounding soils and waters. Today, there is little visible trace of any.

During the summer of ’72, the waters surrounding Three Mile Island were probably viler and more polluted than at any other time during the existence of the nuclear generating station there. And little, if any of that pollution originated at the facility itself.

The Susquehanna’s floodplain and water quality issues that had been stashed in the corner, hidden out back, and swept under the rug for years were flushed out by Agnes, and she left them stuck in the stinking mud.

October 5, 2020October 5, 2020

A Visit to Rocky Ridge

Early October is prime time for hawk watching, particularly if you want to have the chance to see the maximum variety of migratory species. In coming days, a few Broad-winged Hawks and Ospreys will still be trickling through while numbers of Sharp-shinned Hawks, Cooper’s Hawks, Northern Harriers, and falcons swell to reach their seasonal peak. Numbers of migrating Red-tailed and Red-shouldered Hawks are increasing during this time and late-season specialties including Golden Eagles can certainly make a surprise early visit.

If you enjoy the outdoors and live in the southernmost portion of the lower Susquehanna valley, Rocky Ridge County Park in the Hellam Hills just northwest of York, Pennsylvania, is a must see. The park consists of oak forest and is owned and managed by the York County Parks Department. It features an official hawk watch site staffed by volunteers and park naturalists. Have a look.

The hawk watch lookout is reached by following the well-marked trail at the north side of the large gravel parking area in the utility right-of-way at the end of the park entrance road (Deininger Road).

The Rocky Ridge Hawk Watch lookout includes outcrops of bedrock, a viewing deck, and grassy areas suitable for lawn chairs.

The bedrock at the lookout is an unusual quartz-cemented conglomerate that forms the Hellam Member at the base of the Cambrian Chickies Formation.

Experienced hawk watchers conduct an official count of raptors and other birds during the autumn migration in September and October each year. Visitors are welcome. The view is spectacular. Check out the concrete columns glowing in the sun to the north of the lookout.

It’s the cooling towers at the Three Mile Island Nuclear Station and the smoke stacks at the Brunner Island Steam Generating Station. Conewago Falls is located between the two.

Interpretive signage on the hawk watch deck includes raptor identification charts.

A migrating Osprey glides by the lookout.

Throughout the month, migrating Sharp-shinned Hawks will be flying in a southwesterly direction along ridges in the region, particularly on breezy days. They are the most numerous raptor at hawk watches in the lower Susquehanna valley during the first half of October.

A Peregrine Falcon quickly passes the Rocky Ridge lookout. These strong fliers often ignore the benefits provided by thermals and updrafts along our ridges and instead take a direct north to south route during migration.

And a little while later, an adult Red-tailed Hawk follows.

Bald Eagles, including both migratory and resident birds, are seen regularly from the Rocky Ridge lookout.

Other diurnal (daytime) migrants are counted at Rocky Ridge and some of the other regional hawk watches. Massive flights of Blue Jays have been working their way through the lower Susquehanna valley for more than a week now. Local hawk watches are often logging hundreds in a single day.

The utility right-of-way within which the Rocky Ridge Hawk Watch is located can be a great place to see nocturnal (nighttime) migrants while they rest and feed during the day. Right now, Eastern Towhees are common there.

An uncommon sight, a shy Lincoln’s Sparrow (Melospiza lincolnii) in the utility right-of-way near the hawk watch lookout. This and other nocturnal migrants will take full advantage of a clear moonlit night to continue their southbound journey.

If you’re a nature photographer, you might be interested to know that there are still hundreds of active butterflies in Rocky Ridge’s utility right-of-way. Here are a few.

To see the daily totals for the raptor count at Rocky Ridge Hawk Watch and other hawk watches in North America, and to learn more about each site, be certain to visit hawkcount.org

March 25, 2020March 26, 2020

Three Mile Island Anniversary Cancelled

The remains of the Three Mile Island Unit-2 reactor building (right) and cooling towers (left) on September 20, 2019, the day the neighboring Unit-1 reactor was shut down for the final time, thus ending nuclear power generation at the site.

To avoid any theft of the limelight from the country’s miscreants who are currently using the year’s most worrisome virus strain , SARS-CoV-2, as a cover for wealth realignment and self-promotion, this week’s 41st anniversary observance of the 1979 nuclear accident at Three Mile Island has been cancelled. The planned community reenactment festivities will not be held this year.

We will not be recreating the run on the stores or the hoarding of toilet paper, ammunition, food, booze, smokes, prophylactics, and pet treats. Though not sanctioned by the official event, undocumented pharmaceutical distributors will still be vending product to the self-medicated at the usual locations, reminiscent of 1979 commerce.

The Friday night disco get-together featuring authentic vintage 8-track tape music is called off, which of course means that commemorative T.M.I.-2 anniversary t-shirts will not be available for sale this year. If you were thinking of attending, be assured that you can find audio of the Bee Gees’ “Stayin’ Alive” on the internet and play it three times just like it would have been repeated at the dance. You can find other event favorites online too, including the Trammps’ “Disco Inferno”.

The annual “evacuation excursion” to the mountains of Pennsylvania led by the gasoline and gunpowder gang to terrorize the countryside with four-wheel drive trucks, all-terrain vehicles, fireworks, and random weapon discharges is scrubbed. The traditional trash burning in the fire pit on Saturday afternoon and weenie roast scheduled for Saturday night are nixed. Regular participants will have to inhale and ingest their dose of dioxins somewhere else this year.

The consortium of local college drama clubs will not be presenting their popular horror play “It’s Gonna Blow Up”, featuring authentic rumors and supposition from actual news media reports about the 1979 accident. Mock briefings featuring posturing politicians trying to patronize their donors without endangering their reelection prospects will not be held and have been eliminated from the slate of activities—they seem too familiar to be of any interest. A slapstick comedy interpretation of bureaucrats trying to assume authoritarian power to implement an emergency plan that never existed has been postponed until a future event.

Speakers due to share their insights at this year’s gathering have been asked to return next time. We’re pleased that each has agreed. It’s a splendid roster of advocates both for and against nuclear energy, each of whom has shamelessly abandoned their integrity to sustain a do-nothing career that protects them from ever breaking into a sweat. As usual, these appearances will be scheduled as the final feature of the weekend to assure a prompt dispersal of the crowd.

We hope to see you all sometime soon. In the meantime, please remember to use the euphemism “essential workers” when referring to the expendable labor that is out there protecting public health and assuring that everyone can keep shopping. We as a nation would hate for them to realize their worth—they may expect to be better compensated.

October 17, 2019October 17, 2019

No Deposit/No Return

Late this afternoon, despite a cold bone-chilling rain, news media and crowds of onlookers gathered along the Susquehanna shoreline upstream of Three Mile Island at the small town of Royalton to catch a glimpse of the removal of a downed aircraft from the river. Back on October 4, a single-engine Piper PA46 Malibu was on the final leg of an approach to runway 31 at Harrisburg International Airport when it lost power. The pilot and passenger were uninjured during the emergency “splashdown” in the shallow water just short of the runway.

Recovery crews begin installing a set of slings around the downed plane’s fuselage. It rests on York Haven Diabase bedrock in water about three feet deep. Today’s heavy rains could raise the river level and float the plane into deeper water, so there is some urgency to complete its removal.

The Sikorsky S-61 recovery helicopter arrived just as the rain subsided. Its hoist cables were quickly attached to the rigging that had been placed around the plane.

Slack in the hoist cable and harness assembly was taken up.

The flooded fuselage was allowed to drain before proceeding, greatly reducing the aircraft’s weight and the load on the helicopter and hardware.

The plane was transported to its original destination, Harrisburg International Airport, located just one mile away. The timing of the recovery was impeccable. Soon after its completion, a gusty wind swept down the river valley. Colder air is expected to blow in throughout the remainder of the evening and through the morrow. Meteorologists are calling the developing weather system a “bomb cyclone”.

Not everything that finds its way into the river generates as much effort to recover it. It’s a case of no deposit/no return I suppose.

September 20, 2019September 25, 2019

…You Don’t Have Three Mile Island To Kick Around Anymore!

At 12:07 P.M., E.D.T. today, forty-five years and eighteen days after being commissioned into commercial service on September 2, 1974, the Three Mile Island Nuclear Generating Station’s Unit 1 reactor was shut down for the final time. There will be no refueling. There will be no more electricity furnished to the grid by the plant. It is henceforth a user, not a producer, of energy.

Here’s the final shutdown, in pictures…

Work began to build the Three Mile Island Nuclear Generating Station in 1968. In this photo taken on July 7, 1970, one can see that Unit One’s reactor containment building and cooling towers have been erected and that the excavation and early construction of the ill-fated Unit 2 is underway. (United States Department of Agriculture Agricultural Stabilization and Conservation Service image)

11:15 A.M., E.D.T. Water vapor clouds rise from the Unit 1 cooling towers (left) during the plant’s final hour of electricity generation. Smoke in the center of the photo is from a diesel-powered auxiliary steam generator that is used during the shutdown process.

11:40 A.M., E.D.T. Three Mile Island Unit 2 (left), and Unit 1 (right), just prior to the latter’s final shutdown. Unit 2 is presently in monitored storage. It has not operated since the 1979 accident. Unit 1 did not operate for 6 years following Unit Two’s shutdown. Since being permitted to restart, Unit 1 has continued to be a reliable pressurized water reactor electricity generating system.

12:00 Noon Unit 1 in the process of shutdown. Control rods were inserted into the fuel assembly and “zero percent” generation was marked at about 12:07 P.M., E.D.T. By then, the heat release rate in the core had dropped to 10% of the level produced while a full-capacity reaction is occurring.

Just after the reactor was placed in cooling mode, a press conference got underway at the Three Mile Island Training Center, site of all the press action during 1979’s Unit 2 accident. Dauphin County Commissioner Mike Pries lamented the eventual loss of 675 full-time jobs at the T.M.I. facility. He noted that if the plant were not now closing, 1,000 workers would be arriving to refuel and service the reactor. The local economy will now miss out on the 36,000 “room nights” of revenue previously generated by skilled labor remaining in the area for a little more than a month to complete a shutdown refueling.

Dave Marcheskie, Exelon’s Senior Site Communications Manager at Three Mile Island, reported that by shutdown, Unit 1 had completed a record 709 continuous days of safe and reliable energy production. Despite being permitted through 2034, in 2017, Exelon Corporation announced plans to shut down the T.M.I. Unit 1 reactor early, citing an inability to operate the facility profitably while competing with natural gas-fired generators and subsidized producers including wind turbines.

It’s always lots of fun at a Three Mile Island news conference when there’s a dissenting point of view. I’ll bet Uncle Tyler Dyer knows this guy, although he’s probably upset with him for not wearing one of the custom shirts he makes. Better luck next time Uncle Ty.

12:59 P.M., E.D.T. Nearly one hour after shutdown, steam clouds continue to rise from the Unit 1 cooling towers. One thousand gallons per minute or more of water are circulating through the primary (reactor) cooling loop to absorb the energy produced by the “leftover” fission products that are decaying in the core.

1:23 P.M., E.D.T. The last remaining heat from the core is transmitted by a primary cooling loop inside the reactor containment building to a secondary loop that would, when making electricity, drive the steam generator in the neighboring building. A third loop, which never enters the reactor, cools the condenser on the secondary loop, and finally surrenders its heat in the cooling towers. Unit 1 can use “once-through” river water to direct cool the condenser during shutdown.

2:11 P.M., E.D.T. The cooling process progresses.

2:29 P.M., E.D.T. Wispy water vapor clouds are gradually diminishing in density at the top of the Unit 1 cooling towers (right).

2:29 P.M., E.D.T. Yes, that is a water skier behind the boat.

2:33 P.M., E.D.T. The periods of time without visible steam clouds lengthen as the heat release rate from the reactor core continues to plummet toward a cold shutdown.

Environmental monitoring will continue on and around Three Mile Island during the decades of cleanup and decommissioning to come.

By 2074, as the centennial anniversary of Unit One’s commissioning comes around, the cooling towers and most of the other buildings at T.M.I. should be gone. By then, Three Mile Island may look more like it did during the years before construction ever began. By then, nothing but a historical marker will be left to tell future generations of the events that transpired during the power plant’s operating years. Here’s an idea for a sign to go with it: “Three Mile Island N.W.R. (Nuclear Wildlife Refuge), people keep out!” By 2074, maybe society will have enough sense not to build and live on beaches, in tidal estuaries, and in floodplains. Wouldn’t that be nice? (United States Department of Agriculture Commodity Stabilization Service image-November, 1956)

June 25, 2019June 25, 2019

Uncle Ty’s T-shirt

It had been quite a few years, decades actually, since Uncle Tyler Dyer and I had visited the State Museum of Pennsylvania, formerly the William Penn Museum, in Harrisburg. Several days ago we decided to stop by to see what’s new.

I was fussing around with the official “Life in the Lower Susquehanna Watershed” camera while walking slowly down an entrance corridor when I heard Uncle Ty exclaim from up ahead, “Hey man, that’s my T-shirt!”

There it was, neatly screen-printed on luxurious , but functional, blended cotton and polyester, just like the one Uncle Ty wore forty years ago. This priceless gem was no iron-on job. It was the real thing, just like Coke, but a little bit more expensive.

A T.M.I. T-shirt just like the one Uncle Ty wore back in 1979 is among items on temporary display at the State Museum of Pennsylvania to mark the fortieth anniversary of the Unit-2 accident.

Uncle Ty said that, other than his own artistic creations, his T.M.I. T-shirt was the only one he wore during the summer of ’79. It even had spots of hardened wax in the fabric around the belly section where his candle had dripped during one of the anti-nuclear energy protest vigils he attended.

I wasn’t so certain, I thought he had a few others in his rotation back then. All those corporate beer brand and pop music group T-shirts were really popular. And “Grease”, Uncle Ty really liked Olivia Newton-John back then. He had a “Grease” T-shirt for sure. Then I remembered, and I reminded him, “You were wearing a Buck Tractor Pulls T-shirt back then, weren’t you?” I was sure of it, nice artwork of a hopped-up farm tractor on the front and “See You at the Buck” across the back.

“No way man,” he retorted, “There’s no way I went down there to waste a Saturday night with that gasoline and gunpowder gang. I would have sooner spent a Saturday night getting a tooth worked on by an angry intoxicated dentist!”

Oh well, everybody has there own idea of a good time.

June 13, 2019June 12, 2021

Three Mile Island, Thunderstorms, and Two-headed Cows

We’re beginning to worry about Uncle Tyler Dyer. It’s been almost a month since a tornado descended from an eastbound cloud that first passed by Three Mile Island, and from him we’ve heard not a word about it. And the rainfall totals during the past year, well above normal and record setting, but not a peep from him about it. The floods too, and the gusty thunderstorms that either seemed to strike only our town, or would instead let us high and dry while passing off to the north or south. For forty years, from Uncle Ty’s point of view, these phenomena were all attributable to those towers down at Three Mile Island. He would say, “Man, you know the lightning in that thunderstorm was terrible because of T.M.I. You know that, don’t you?”

If you happen to live in the lower Susquehanna valley, you’ve probably heard comments like that at the local diner, taproom, or gathering of family and friends. Many are offered by good-humored folk, in jest, to enliven the conversation. It makes a chat about the weather a bit more exciting. Then to, there are those who became extraordinarily suspicious of the nuclear facility at Three Mile Island after the accident. To them, any deviation from the status quo must be caused by those big towers down there. Even if they don’t fully believe what they’re saying, it matters that they don’t miss the chance to get in a jab, even if it’s a glancing one. That’s Uncle Ty. He sees that plant in a different light than we do, from a different perspective. To him, Three Mile Island is the ultimate symbol of corporate evil. It’s not about the fuel used to operate the reactor. The invisible threat of radioactivity is a metaphor for the secretive operations of sinister big business. Those towers are a collection of monoliths representing greed, interlocking corporate directorships, and immunity from accountability. And no one is going to change his mind.

Everyone has their own perception of Three Mile Island.

If you remember reading, watching, or listening to news reports in the weeks and months following the accident at Three Mile Island, you recall stories from farmers and other residents living in the vicinity of the plant who described diverse irregularities in the health of domestic animals and in populations of wildlife there. For some, these reports left a lasting impression of conditions near the site of the accident.

The Pennsylvania Department of Agriculture, the Environmental Protection Agency, and the Nuclear Regulator Commission conducted an investigation into these reports. Because the levels of radiation released during the accident were barely above background levels, it was going to be difficult to detect any changes in animals or plants that could be definitively linked to operations at Three Mile Island or the accident there.

Upon evaluating cases for which sufficient data had been preserved or animals were available for examination, investigators failed to find any animal deaths, injuries, diseases, deformities, or stillborn young caused by known effects of ionizing radiation exposure. Anemic conditions would have been expected in animals exposed to significant doses of radiation, but cases of anemia were not found. For the animal fatalities reported, their numbers generally fell within the expected mortality rates for breeding, raising, and keeping the species involved. For the cases examined, no link could be made to exposure to ionizing radiation or byproducts released during the operation of T.M.I. or the accident at Unit 2. Instead of a pattern of mortality and illness consistent with ionizing radiation exposure, investigators instead found a wide-variety of problems considered common to animal keeping.

During the investigation, some of the causes for domestic animal afflictions were identified and, when possible, proper remedies were recommended. Animal husbandry errors, accidents, and disease accounted for most of the deaths, disabilities, and reproduction failures in domestic animals. The occurrence of stillborn or deformed pets was attributed to a variety of diseases and developmental problems that are frequently associated with the symptoms described by pet owners. Poultry eggs that failed to hatch were believed to be infertile or were not maintained at the proper temperature during incubation. Many of the physical ailments in adult dairy cows were traced to mineral deficiencies in the feed. Cases of rickets were found among steers at two different farms. Supplements mitigated these abnormalities in the involved herds. Some cows were found to be suffering from bacterial or viral infections. A few dairy animals had developed mastitis, an inflammation often caused by bacterial infection of the udders. Following diagnosis, herdsmen were able to initiate treatment. Among livestock, fertility and reproductive deficiencies were generally traced to nutritional shortcomings or disease. Those farmers needing further help troubleshooting breeding difficulties were referred to the Pennsylvania Department of Agriculture’s Diagnostic Lab.

The majority of people not living in the lower Susquehanna valley at the time paid little attention to the results of the investigations. Such reports are often lengthy and boring, not as exciting as the stories of mutants and catastrophe, and not as memorable. Naturally, the closer you lived to T.M.I., the more informed you probably were about it; you knew first-hand how life was both before and after the accident. Those living elsewhere were sometimes left with exaggerated recollections based upon those initial news stories from the scene.

While traveling some years ago, Uncle Ty was astounded by the perception folks from outside Pennsylvania had of the place he calls home. He told us of one incident in particular. Uncle Ty had gone to the South Bronx in New York City to participate in an “End the Violence” protest. Gunfire and murder were an occurrence of epidemic proportions on street corners there at the time. It turned out that the protest was a poorly attended flop. It happened to be Bat Day at Yankee Stadium, so everyone had gone there instead. During his extended lunch break, Uncle Ty struck up a conversation with a local, a likeable public safety worker who lived and worked in the South Bronx. Ty expressed some sympathy for the stressful conditions the fellow had to endure as a resident there. The guy appreciated his sentiments, but didn’t think he had it too tough. When Ty told him that his home was near Three Mile Island, the guy shook his head in pity and said, “yeah, I hear it’s pretty bad out there, all the two-headed cows walkin’ around and s…”. A guy from one of the most dangerous neighborhoods in the country felt really sorry for him. Even Uncle Ty was caught off guard by that one, but it wasn’t the last time he heard it either.

Today, Uncle Ty has us all pondering. Has he given up on Three Mile Island’s grand towers as the primary factor affecting all meteorological irregularities in the lower Susquehanna? Will we ever hear of a cooling tower induced drought again? What will he turn to? It’ll have to be something big. A causative force that no one can quite prove or disprove, mysterious enough to keep everyone guessing if he really knows something no one else knows. I wonder what it’ll be. No matter what it is, it just won’t be the same as hearing, “Man, don’t you know? T.M.I. did it.”

This two-head calf specimen from the lower Susquehanna valley has been in the natural history collection at the North Museum, Lancaster, PA, since long before the construction of Three Mile Island’s nuclear generating facility and reactors began.

SOURCES

Gears, G. E., G. Laroche, et al. (1980) Investigations of Reported Plant and Animal Health Effects in the Three Mile Island Area. U.S. Environmental Protection Agency. Las Vegas, NV.

April 1, 2019June 12, 2021

Three Mile Island 40: Part Three

A sixteen year-old skinny kid driving a Ford Pinto on a Saturday afternoon in late March, 1979, might be perceived by some observers as a metaphor for the accident at Three Mile Island on that same day. When experiencing a rear-end collision, the fuel tank on these little compact cars had been known to explode, sometimes with fatal consequences. They quickly gained a reputation as a deadly hazard on the highway. Despite a recall and engineering fix to prevent the fuel tank from failing, the Pinto remained cursed, and it was henceforth looked upon as a dangerous creation of man that best be avoided if you wished to remain in good health.

For a sixteen year-old, a Pinto functioned just fine as a frugal form of transportation. So in a hideous limey-yellow one, a kid showed up at the Three Mile Island Observation Center to have a look around. There, hundreds of photographers, reporters, and journalists had gathered to try for their angle on the latest news from the accident scene. Cars and news vans lined the state road, Pennsylvania Route 441, in front of the facility. Anything that moved was photographed and interviewed. The story of the day, March 31, 1979, was the impending explosion of the hydrogen gas bubble in the Unit 2 reactor. It was the sensation that they had waited for.

By Saturday, the N.R.C. was growing concerned about the potential of a hydrogen explosion within the Unit 2 reactor. Hydrogen was formed early in the accident when hot steam in the high-temperature core reacted with the zirconium alloy in the fuel rod cladding and produced primarily zirconium dioxide and hydrogen gas. Some of this gas had been vented into the reactor containment building. There, it mixed with atmospheric oxygen and ignited when a block valve switch was operated during the late morning of day one. Operators recalled hearing a “whooshing” sound just after flipping the switch. It is believed they did not really hear the explosion or burn-off of the gas, but rather the activation of a water spray system in the building in response to it.

The N.R.C. learned on Friday of this event that had occurred two days earlier. Harold Denton wanted to know if radiolysis of water inside the reactor was producing additional hydrogen and, more critically, oxygen. Many in the N.R.C. were convinced by their calculations that enough oxygen could be produced in the coming days to make the existing hydrogen bubble explosive. Denton wanted to know for sure, and ordered a team to enlist outside help to determine a timeline for this radiolysis. He also assigned a team to determine the parameters and details for a possible explosion.

Meanwhile, this story had gone public. Upon hearing the words “nuclear” and “explosion” together in news reports, the memories of old Civil Defense promotions came back to haunt local residents, and the nation. For many, the horrific image of a nuclear explosion had been projected into their perception of the accident. An explosion similar to an atomic bomb was not possible in the reactors of the type used for energy production in the United States, but few sleep well with visions of mushroom clouds dancing in their heads. For those on the fence deciding whether to stay or go, this was it, the last straw. In response to these broadcasts, more residents left the lower Susquehanna region on Saturday. As they went out, press personnel moved in, many setting up camp at the Three Mile Island Observation Center.

At 2:45 P.M., reporters at N.R.C. headquarters in Bethesda were told that a 10 to 20 mile evacuation might be necessary as a precaution if the decision was made to attempt to force the hydrogen bubble out of the reactor.

An Associated Press story went public at 8:23 P.M. quoting N.R.C. officials as saying that the hydrogen bubble could explode spontaneously.

This information kept local Civil Defense personnel up through the night answering phone calls from the worried residents who remained in their homes. They wanted to know what to do, but the local offices and P.E.M.A. were getting very little advice from the Lieutenant Governor’s and Governor’s offices. The state B.R.P. was still providing them with radiation information, but beyond that, Civil Defense offices were on their own for the night.

Harold Denton, being informed that President Carter was coming to Three Mile Island the next day, wanted things clarified. He told his deputy Victor Stello, Jr. to solicit sources outside the N.R.C. on the oxygen issue. Stello had fielded a call from the White House at about 9:00 P.M.. In response to the A.P. story, he told a presidential aide that he did not share the concern of others at the N.R.C. regarding the production of oxygen in the reactor. He and some engineers at Babcock & Wilcox, designers of the reactor, were among the few who shared this opinion. (Also, engineers at Babcock & Wilcox analyzing the effects of an explosion, should one occur, were confident that water and steam, if maintained in the pressurized reactor containment vessel, would reduce the pressure of an explosion to within the capabilities of the vessel to contain it.)

On Sunday morning, April 1, 1979, Victor Stello made his case to Harold Denton explaining why he thought there would be no hydrogen explosion in the Unit 2 reactor. He told Denton that pressurized water reactors like TMI-2 routinely have free hydrogen circulating in the coolant. The majority of oxygen produced by radiolysis would bind with this hydrogen and simply make more water.

President Carter and First Lady Rosalynn Carter aboard the Marine One helicopter en route from the White House to Harrisburg International Airport on Sunday, April 1, 1979. (White House Staff Photo- National Archives)

Just minutes before the President landed at the Air National Guard facility at Harrisburg International Airport at 1:00 P.M., the N.R.C.’s Joseph Hendrie and Roger Mattson, who had been researching the explosion question, arrived at a hangar there to present their case to Denton.

Quoted in the “Report of the President’s Commission on the Accident at Three Mile Island”, Mattson described the scene:

“…And Stello tells me I am crazy, that he doesn’t believe it, and he thinks we’ve made an error in the rate of calculation…Stello says we’re nuts and poor Harold is there, he’s got to meet with the President in 5 minutes and tell it like it is. And here he is. His two experts are not together. One comes armed to the teeth with all these national laboratories and Navy reactor people and high faluting PhDs around the country, saying this is what it is and this is the best summary. And his other (the operating reactors division) director saying, “I don’t believe it. I can’t prove it yet, but I don’t believe it. I think it’s wrong.”…”

View from Marine One as the President and First Lady pass over Conewago Falls and approach the Three Mile Island Generating Facility. Marine One would land just upriver at Harrisburg International Airport. (White House Staff Photo- National Archives)

Harold Denton (left) briefs President Jimmy Carter and Pennsylvania Governor Richard Thornburgh. Denton’s deputy, Victor Stello, Jr., looks on. (White House Staff Photo- National Archives)

President Jimmy Carter was no stranger to nuclear reactors, or reactor accidents for that matter. A 1947 graduate of the United States Naval Academy, Carter eventually worked his way into Captain (later Admiral) Hyman Rickover’s nuclear command. In 1952, Rickover (known as the father of the Nuclear Navy) ordered the 28 year-old Lieutenant Carter, then assigned to the Naval Reactors Branch at the U. S. Atomic Energy Commission, to the scene of a partial meltdown of a research reactor at Chalk River Laboratories in Ontario, Canada.

There, Carter led a team of 23 men. Their job was to shut down and dismantle the damaged reactor. They built a mock-up of the reactor on a tennis court and practiced taking turns performing the tasks to complete the job. This model would be used to track the progress of the project in the actual reactor. When a bolt, nut, or other part was removed in the real reactor core, it would be removed from the model as well.

Following these preparations, men suited up in protective gear and were lowered into the reactor, one man at a time, to do the work. Each man in the rotation was permitted to be in the reactor for only ninety seconds, then he was hoisted back out. During every one of these short journeys to the core, each worker, including Carter, received a dose equivalent to a year’s worth of allowable radiation today. Carter’s urine was radioactive for six months afterward.

President Carter’s earlier experiences in Rickover’s Navy, particularly at Chalk River, gave him exceptional familiarity with conditions arising from the accident at Three Mile Island in 1979.

The President and his party left their limousines near the east shore gate and entered Three Mile Island by school bus. Denton’s arrival on Friday and Carter’s tour of the plant on Sunday had a calming effect on the anxieties of residents in the lower Susquehanna region. (White House Staff Photo- National Archives)

James Floyd, supervisor of Unit 2 operations, explains the situation to the Carters, Governor Thornburgh, and Harold Denton. (White House Staff Photo- National Archives)

The President and Governor look over some of the metering devices in the control room. (White House Staff Photo- National Archives)

The President and First Lady receive assistance as they shed their protective boots and prepare to leave the plant facility. (White House Staff Photos- National Archives)

After returning to the limousines by school bus, the President and his party motorcade to Harrisburg International Airport and the awaiting Marine One helicopter. (White House Staff Photo- National Archives)

Following the briefing of the President and Governor, Stello, Hendrie, and Mattson went back to the N.R.C.’s temporary office to try to rectify the oxygen and explosion problem. After consulting with some additional outside sources, including Westinghouse and General Electric, they had the answer. The hydrogen bubble would NOT explode. It was 3:00 P.M.

At just before 4:00 P.M., there was a new push from the N.R.C. in Bethesda to start an evacuation within two miles of the plant. Chairman Hendrie informed them—there is NO danger of an explosion. The teams in Bethesda would find concurrence with Stello, Hendrie, and Mattson by later that evening. On Monday, the N.R.C. trickled out the good news, but would not outright admit that their calculation errors had caused a near panic. Instead, they claimed that they had been a little too conservative in their estimates.

Shortly following the President’s visit, or during it, the hydrogen bubble began dissipating. The public wasn’t made aware of it until the following day, Monday, April 2. By then, operators for the utility reported that it was nearly gone. No direct action had been taken to get rid of the bubble, its disappearance was mysterious, yet welcome.

Nobody knows how many people evacuated the lower Susquehanna valley during the accident. It is generally believed that over 100,000 left for at least the weekend. Some communities, such as Goldsboro, a small town overlooking Three Mile Island’s reactors from the York County side of the Susquehanna, may have experienced evacuation rates approaching ninety percent. In the majority of areas more distant from the plant, the rate was well below fifty percent. Most of those who left their homes began returning as schools reopened during the mid-week.

During that first weekend, the press was angling to get officials to speculate on the probability of the occurrence of a catastrophic core meltdown. No one had realized that the meltdown had already happened, on day one. It was determined in 1987 that in excess of half of the more than 100 tons of uranium oxide fuel had melted during that first morning. In 1989, 20 tons of molten fuel was discovered to have flowed to the bottom of the reactor vessel and solidified into a slag-like mass there. Fortunately, Unit 2’s pressurized reactor vessel had kept the catastrophic core meltdown contained within its five-inch-thick steel structure.

Crews on Three Mile Island worked faithfully to manage gases and continue the cooling of the reactor core. Cold shutdown of the reactor (reduction of temperatures to below the atmospheric boiling point of water) would take another week, the full cleanup and de-fueling would take more than a decade. Unit 2 was placed in monitored storage in 1993, and will be fully decommissioned simultaneously with the Unit 1 reactor when the latter is permanently taken out of service.

On the day of his visit to Three Mile Island, President Carter signed executive orders activating the Federal Emergency Management Agency (F.E.M.A.), a new entity formed to house Civil Defense and disaster preparedness, with the latter of the two becoming the greater focus of its mission.

Forty years after his visit to Three Mile Island, Jimmy Carter, at age 94 ½ years, had become the longest-lived President in American history. We wish he and Rosalynn many more happy years.

Finally, what shall we think of the risky travels of a sixteen year-old? Was the bigger hazard the act of being inside a Ford Pinto while driving to Three Mile Island on Saturday, March 31, 1979, or was it the act of being at Three Mile Island itself on that afternoon? We’ll let you decide.

SOURCES

Forman, Paul, and Sherman, Roger. 2004. Three Mile Island: The Inside Story. Web presentation based upon Smithsonian National Museum of American History exhibit, as accessed March 28, 2019. https://americanhistory.si.edu/tmi/index.htm

Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office, Washington, D.C.

Milnes, Arthur. January 28, 2009. “When Jimmy Carter Faced Radioactivity Head-on”. The Ottawa Citizen.

March 30, 2019June 12, 2021

Three Mile Island 40: Part Two

It was forty years ago today. The civics teacher had a hook on stick, and he was under orders to use it. He was trying his best to draw the water-stained paper blinds down over the tall old single-pane glass windows that covered the length of the outer wall of his west-facing room. You understand, this was not something he was doing of his own accord. He was a veteran educator, one of those teaching the offspring of his students from a previous generation. He was no tyrant merely wanting to deny his pupils the distractions of a beautiful spring day outdoors. He was ordered by the coffee cup brigade in the front office to close the windows and draw the shades. The safety of the students is at stake!

As his third class of the day entered the room, the instructor enlisted the help of a couple of taller students to try to get some of those stubborn window coverings pulled down. No luck. Class would commence with blinds up, down, and in between. Today’s topic: the dangers of nuclear energy. As usual, it was something of an open discussion of current events. All points of view were encouraged.

Few noticed the town fire siren howling away during the first minutes of the oratory. That happened every once in a while, so it wasn’t so remarkable. The class transformed from debate and dialog to a practical demonstration a little while later when fire trucks began circulating through the streets near the school broadcasting muffled incoherent warnings of some sort to the residents of adjacent neighborhoods.

Within moments there was clamor in the hallways as several students were banging locker doors and making off with their wares. Soon the old classroom phone that hung as a decoration on the wall near the doorway began making an obnoxious noise. What does this mean? What should we do? It never made a sound before. The dedicated educator walked over and picked up the receiver. He timidly said, “Hello?” He listened carefully, acknowledging the caller from time to time, then he said, “O.K.” After hanging up the little-used device, he walked over to a startled girl and simply told her to gather things and report to the office, one of her parents was here to pick her up.

The old sage walked back to the lectern and just stared around at the quiet faces in the room , not a word was said until the phone rang again. He looked over toward a skinny sixteen year-old kid, a late-bloomer, seated near the half-shaded windows and quietly said, “Mr. C—, you have duties to perform, don’t you?, you may leave.” Then he turned to answer the phone for the second time. The skinny kid departed the school building posthaste.

Three Mile Island Unit 2 (left) in monitored storage. Three Mile Island Unit 1 (right) generating electricity. March 28, 2019.

Since the beginning of the accident, operators of the Unit 2 reactor had been spending a considerable share of their time and effort coping with noncondensible gas in Unit 2’s coolant system. Not only was there growing concern that a build-up of Hydrogen around the top of the reactor core was preventing coolant from reaching the fuel assemblies, but gas was causing problems in other portions of the cooling system as well. One component in particular, a make-up tank used to store water that is used as needed to increase the volume of coolant in the primary cooling system, was of concern in the early morning hours of Friday, March 30, 1979. Its relief valve had activated at least once due to excessive pressure. Gauges read that gases had displaced all of the water from the tank.

Just before 7:00 A.M., operators decided to open a valve to purge the radioactive gases from the make-up tank into the waste gas decay tanks where it is collected and stored by design. The venting began at 7:10 A.M. Aware that a header leaks in this system, and that any leaked gas will enter the auxiliary building and be discharged to the atmosphere from its vent stack, a helicopter monitoring flight is requested to collect samples above the plant and its perimeter. Almost an hour into the venting process, at 8:01 A.M., a radiation reading of 1,200 millirems per hour (mr/hr) is measured 130 feet directly above the vent stack. A reading of only 14 mr/hr was taken along the boundary of the facility site. This was an expectable set of readings. During a short venting procedure involving the make-up tank on the previous day, a sampling flight measured 3,000 mr/hr fifteen feet above the stack .

Confident that they can now keep gas accumulation in the make-up tank under control by “puffing” it clear on a regular basis, and again having the ability to use the make-up tank to equalize coolant levels, the process is a success. The operators are on to the next step as they strive to get the reactor into a cold shutdown.

Friday’s memorable troubles resulted from a series of inaccurate reports of the 1,200 mr/hr reading taken above the auxiliary building vent stack. For the next ninety minutes, the 1,200 mr/hr figure shot like lightening through a chain of phone calls that left Three Mile Island and made its way through state-level and county-level offices and found smooth sailing through the Nuclear Regulatory Commission (N.R.C.) and landed right in the middle of meeting of the latter in Bethesda, Maryland.

But first, at 8:45 A.M., a Telex message arrives at the N.R.C.’s Incident Response Center:

“The seal return to the makeup tanks was causing excessive gas pressures in the makeup tank which was directed to the waste gas decay tanks which were full. The waste gas tanks were being released to the stack. Pennsylvania Civil Defense was being notified by Licensee.”

This errant message indicates that the highly radioactive contents of the waste gas decay tanks, which are NOT full, can be expected to vent from Three Mile Island with some regularity for the foreseeable future. At 9:00 A.M., the N.R.C.’s Lake Barrett carries the Telex into a meeting of the agency’s Executive Management Team (E.M.T.). Alarmed by the news, they ask Barrett to calculate what an off-site radiation dose might be with the anticipated releases. Ironically, Barrett arrives at a figure of 1,200 mr/hr for a person at the site boundary, a value exceeding the Environmental Protection Agency (E.P.A.) threshold for evacuation of sensitive persons. Within minutes, the E.M.T. receives a phone call from Karl Abraham, the N.R.C. press officer at Governor Richard Thornburgh’s office in Harrisburg. He’s on the speakerphone and wants to know if the reports of 1,200 mr/hr readings above the “cooling towers” are true. This is the first the E.M.T. has heard of the 1,200 mr/hr number at the site, and because it matches Barrett’s calculation for off-site releases from full waste gas decay tanks, they assume it to be an off-site number and forget that Abraham was asking a question. Following a discussion, Harold Denton, Director of Reactor Regulation, orders that a recommendation for evacuation out to ten miles in the direction of the plume be given to the Pennsylvania Emergency Management Agency (P.E.M.A.), the state-level Civil Defense agency. This recommendation is delivered at 9:15 A.M. Unfortunately, the location of the 1,200 mr/hr reading was not verified beforehand.

In Harrisburg, Margaret Reilly of Pennsylvania’s Bureau of Radiation Protection (B.R.P.) was trying to verify the N.R.C.’s reasons for the evacuation recommendation. There was some ire because P.E.M.A. received the recommendation instead of the B.R.P., or, better yet, Governor Thornburgh himself. Information available to Pennsylvania agencies showed no reason to evacuate.

Dutifully acting on the N.R.C.’s recommendation, the state notifies Dauphin County Civil Defense, telling them to expect an evacuation order from the Governor within five minutes. The mild temperatures on this Friday were due to a steady wind from the southwest, putting communities in Dauphin County within any possible plume from the Three Mile Island Unit 2 facility. It appeared that communities in Dauphin County, including the city of Harrisburg, would comprise the majority of the evacuation zone. Fire companies, municipal officials, local Civil Defense directors, and others were alerted. Announcements on Harrisburg’s WHP radio advised citizens within five miles of T.M.I. to make preparations and gather supplies for a possible evacuation. The cat was out of the bag.

Governor Thornburgh was very cautious, possessing an understanding of the risks to the public that an evacuation order could cause. He would later be quoted, “In Pennsylvania, P.E.M.A.’s role is to manage the emergency, not to recommend evacuation. P.E.M.A. mentality (during the T.M.I.-2 accident) was akin to being all dressed up with no place to go—leaning forward in the trenches. We had to be careful about that attitude.” Thornburgh knew that ordering an evacuation meant moving patients in health care facilities, possibly at great risk to them. He knew too, that evacuation meant putting helmets in the street—the National Guard.

The Bureau of Radiation Protection had checked the site and conferred with the N.R.C. in Bethesda and was convinced that an evacuation was not necessary. Because of the public broadcasts, phone lines were jammed, so nuclear engineers from B.R.P. are hurriedly en route to the Governor’s office and P.E.M.A. to deliver the facts in person. It’s 9:45 A.M.

At the same time in Bethesda, the E.M.T. had learned that the 1,200 mr/hr reading was not from off-site, but from directly above the vent stack. They were also made aware that the venting had not come from the waste gas decay tanks, but from the make-up tank. And finally, they learned that the waste gas decay tanks were not full, but were accepting gases from the make-up tank as designed. By 10:00 A.M., they rescinded their evacuation order—about the same time that Governor Thornburgh countermanded it.

Too late. By this time people were getting out of town. Schools were overwhelmed as parents showed up to pull their children out of class, one by one at first, then in droves. Sirens were sounding. Broadcasts were telling people to close blinds and windows and remain indoors. The Three Mile Island Unit 2 accident was now the biggest news event in the nation.

Governor Thornburg went on WHP radio at 10:25 A.M. to broadcast a message to residents, attempting to rectify some of the contradictions of the morning. Within the hour, President Carter would call the Governor and assure him of the White House’s full support. He told the Governor that he was sending Harold Denton to the scene forthwith. Denton was to “take charge of the site on behalf of the federal government”.

At local Civil Defense offices in the lower Susquehanna valley, there was a continuous flow of telephone calls from concerned citizens, some of them very frightened. They wanted to know what to do. The ball was rolling, and people with families were becoming more and more inclined to leave.

A skinny sixteen year-old volunteer walked into a community fire station in a small town about six miles from Three Mile Island at about 11:00 A.M. There, the town’s mayor and Civil Defense Director were conferring inside the “Civil Defense office”, a coat closet with a desk and ashtray. The phone was in the adjacent closet, which had more desks and ashtrays. The discussion centered around responsibilities for ordering an evacuation. Following the events at the federal and state level earlier in the morning, it was unclear who had the authority and responsibility to order an evacuation.

The scene was tense, the cigarette smoke was rolling out of the closet for hours as phone calls were made and the chain of command was clarified. Evacuation plans were being worked out in case they were needed. Moving patients from hospitals and nursing facilities was a particularly difficult planning challenge to be tackled. The cloud would persist as the chain smoking continued for the next couple of days. (And those plaid double-knit leisure suits with Flintstones neckties—wow!—it’s a good thing there were no photographs taken of this scene.)

Elsewhere inside the fire station, the sixteen year-old lad and some other volunteers collected the radiological monitoring supplies from the blue and white Civil Defense rescue truck. After gathering some fresh batteries, they ventured outdoors and set up a small monitoring station. Lungs clouded by all the chain smoking inside could be clarified out there. Several metering devices were employed in an attempt to detect radiation. The crew remained at their post through late afternoon, keeping a sharp lookout for the fashion police and enjoying the balmy spring air. It was easy work and no radiation was detected.

In the late 1950s, Civil Defense Light-Duty Rescue Vehicles were provided to some of the larger towns in the lower Susquehanna valley. These trucks were fully supplied with tools primarily intended to remove victims from structures collapsed by detonation of a nuclear weapon. They were often operated by fire companies and used for vehicle accidents and other rescues. The hand-held radiation meters provided with these vehicles were not capable of detecting the low radiation levels found outside the plant perimeter during the T.M.I.-2 accident. (National Archives Image)

Following further consultation with the N.R.C., the Governor held a press conference at 12:30 A.M. He advised pregnant women and pre-school age children to leave the area of a five-mile radius around Three Mile Island. He closed the schools and the few students still in the classrooms were on their way home—or to the mountains for an unscheduled spring holiday.

Harold Denton would arrive at Three Mile Island during the mid-afternoon. Denton found inadequate facilities and communications (no cellular telephone in 1979!) at the T.M.I. Observation Center building where other N.R.C. personnel had set up temporarily. This facility on the east shore of the Susquehanna overlooking the plant was now overrun by scores and soon hundreds of reporters, so Denton set up his base in a home offered by a Met-Ed employee just across the street. He set up his temporary office in the living room, complete with a direct line to the White House. Denton would have his work cut out for him; the hydrogen gas bubble was becoming an increasing concern and the press was storming over the possibility of a catastrophic meltdown. The situation was serious—there would be no BINGO in the fire halls this weekend.

Civil Defense promotions scared the living wits out of a whole generation of parents, then horrified their kids too. Those who grew up with the messages and drills remember them well. (National Archives Image)

People had to wonder if Civil Defense knew what in hell they were talking about. Look closely. When the “BIG ONE” comes we’re planning to take cover in the nearly airtight “finished” cellar, eat potato chips, and bounce around on a trampoline like maniacs while mom cooks canned Spam on a GAS CAMPING STOVE! At least we won’t need any sleeping pills. (National Archives Image)

After years of being terrorized by this public outreach stuff, what appeared to be the “BIG ONE” came on the morning of Friday, March 30, 1979, and the bureaucracy acted like it was the first time they’d ever heard of any of it. The public perceived the apparent compromise of the chain of command. As the contradicting announcements escalated during the third day, residents gave the utility and government a vote of “no confidence”, and they did that voting with their feet. They decided to take the fate of their families into their own hands and evacuate, regardless of recommendations from Civil Defense or other entities. Who can blame them? Radiation or no radiation, their trust was eroded and they were leaving. (National Archives Image)

Thanks Mr. H—, wherever you are!

SOURCES

Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office, Washington, D.C.

Rogovin, Mitchell, et al. 1980. Three Mile Island: A Report to the Commisssioners and the Public. Nuclear Regulatory Commission.

March 28, 2019May 3, 2022

Three Mile Island 40: Part One

The Three Mile Island Unit 2 reactor containment building (center) and cooling towers (left) as they appeared this morning, forty years after the accident and partial meltdown. The Unit 1 reactor continues to generate electricity. Its containment building can be seen along the lower left edge of the Pennsylvania Historical and Museum Commission marker. Steam can be seen rising from the Unit 1 cooling tower on the far right (the second tower is hidden by the marker).

Forty years ago, at just about 4:01 A.M. on Wednesday, March 28, 1979, the Unit 2 reactor at the Three Mile Island Nuclear Generating Station on the Susquehanna River at Conewago Falls “scrammed”—the control rods automatically dropped into the reactor core to stop fission. This occurred in response to the automatic opening of the “Pilot-Operated Relief Valve” (P.O.R.V.) on the pressurizer, a tank designed to prevent the boiling of water in the primary cooling system loop that transfers heat energy from the reactor core to the steam generator. The P.O.R.V. activated when steam in the top of the pressurizer tank was compressed by water that was expanding as it increased in temperature while circulating within the primary cooling system loop.

During normal operating conditions, water in a non-nuclear “secondary loop” is pumped through tubes within the steam generator where it absorbs energy from the hot water in the primary cooling system loop. The heat converts the water in the “secondary loop” to steam for turning the steam turbine and making electricity. At about 36 seconds after 4:00 A.M., a set of pumps “tripped” and stopped feeding water through the “secondary loop” to the steam generator. Within seconds, Unit 2 ceased making electricity. Starting automatically as a failsafe were a set of three “emergency feedwater pumps”, designed to reestablish water flow to the steam generator. A reactor operator verified their start just fourteen seconds after the main pumps “tripped”. Unfortunately, the operator did not notice the panel lights indicating that valves were closed on each of the two lines supplying the steam generator from the emergency pumps. With the “secondary loop” shut down, heat from fission in the reactor core began accumulating within the steam generator and the primary cooling system loop, leading to the P.O.R.V. activation, and the reactor’s “scramming”. The “scram” triggered control rods to drop in 69 tubes among the 36,816 uranium oxide fuel rods to absorb neutrons and stop the chain reaction fission process in the core of Unit 2.

Three Mile Island Unit 2, a pressurized water reactor, used nuclear fission of uranium fuel to heat water circulating in the primary cooling system loop. Within the steam generator, this heat converted water circulating in the low pressure “secondary loop” to steam, which rotated the turbine to drive the generator that produced electricity. Note the “third loop”, which cooled the condenser used to convert steam back to water in the “secondary loop”. Coolant in the “third loop” lost its heat at the base of the cooling towers, then returned to the turbine building for reuse, but did not circulate through the reactor building at any time. (United States Nuclear Regulator Commission Image)

Following the reactor’s “scramming”, an equipment malfunction occurred when the P.O.R.V. failed to automatically close as designed after reducing pressure within the pressurizer vessel on the primary cooling system loop. Unbeknownst to anyone at the time, this equipment malfunction initiated a small “Loss Of Coolant Accident” (L.O.C.A.). Fortunately, the reactor’s High Pressure Injection system (H.P.I.) automatically began pumping water into the primary cooling system to compensate for the loss of coolant through the stuck valve. Even though fission was no longer generating heat, the decaying radioactive materials within the reactor still require continuous cooling until the reactor is brought to cold shutdown.

(Note that the dropping of control rods to effect an automatic scramming immediately reduced the heat output in the core to 160 megawatts, or about 6% of that generated while the fission reaction was occurring. Normally, the heat release rate after the first hour would drop to about 30 megawatts and, over next three hours, to 20 megawatts. This is still a lot of heat—enough to severely damage the fuel assemblies in the core. Twenty megawatts is equivalent to the heat release rate from a big wind-driven apartment fire. It is critical that an uninterrupted flow of cooling water circulates through the core to prevent damage. See the “Riverside Firemen’s Retreat” page on this site to learn how heat release rate applies to the work firefighters do.)

Enter human error, enhanced by insufficient training, missing protocols, and a poorly designed control panel (including, at one point, 100 alarms in simultaneous operation!), and soon the small L.O.C.A. was converted into a destructive meltdown event. An illuminated light on the reactor control panel indicated that a signal had been sent to close the stuck P.O.R.V.; it did not indicate the valve’s position—open or closed. It would be two hours before operators were aware of the stuck valve and would take corrective action to close the back-up “block valve” to stop the leak. Had the H.P.I. system continued operating autonomously throughout this two hour period, no damage to the reactor core would have resulted. However, operators began overriding the emergency H.P.I. system by throttling the flow of 1,000 gallons per minute back to less than 100, hoping to maintain a certain water level in the reactor. This action was inspired by an operator’s doctrine encouraging them not to let the primary cooling system ever “go solid” (fill completely with water). For “extended periods” during the first day of the event, the H.P.I. was throttled back or shut down. It was during these periods that much of the core of the reactor was exposed, resulting in its meltdown.

A television news crew shoots a report marking the 40th anniversary of the accident at Three Mile Island Unit 2 (background). The time was approximately 8:30 A.M.. At about the same time 40 years earlier, word of the incident first leaked to the public.

The Report of the President’s Commission on the Accident at Three Mile Island reveals how haphazard and unorganized the notifications of key persons and agencies were from the very start of the accident. The mayor of Harrisburg at the time, Paul Doutrich, first heard about the accident when he received a phone call from a radio station in Boston inquiring what he planned to do about the nuclear emergency. They had to fill him in first.

The public gained little if any confidence from clumsy and often contradictory public statements made by the plant operator, regulators, and various other government officials during the first days of the event. The oscillations between dire warnings on one hand, and assurances that there is no need to worry on the other, frightened and angered thousands of people in 1979. Memories of these awkward and inconsistent messages continue to be the dominant recollections for many residents of the lower Susquehanna region to this very day.

Here, for your entertainment pleasure, is how the media and general public first learned of the accident on the morning of March 28, 1979 (quoted from the Report of the President’s Commission on the Accident at Three Mile Island)…

“WKBO, a Harrisburg “Top 40” music station, broke the story of TMI-2 on its 8:25 a.m. newscast. The station’s traffic reporter, known as Captain Dave, uses an automobile equipped with a C.B. radio to gather his information. At about 8:00 a.m., he heard police and fire fighters were mobilizing in Middletown and relayed this to his station. Mike Pintek, WKBO’s news director, called Three Mile Island and asked for a public relations official. He was connected instead with the control room to a man who told him: “I can’t talk now, we’ve got a problem.” The man denied that “there are any fire engines,” and told Pintek to telephone Met Ed’s headquarters in Reading, Pennsylvania.”

By late Wednesday afternoon, the reports from the plant indicated that everything was under control. Day one would end with the residents of the lower Susquehanna area presuming they would hear little more of this event. Then came Friday.

SOURCES

Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office. Washington, D.C.

March 28, 2018April 3, 2019

Nuclear Star

“Fear is the darkroom where negatives are developed.”

—Anonymous

I celebrate alone, entering my fortieth year of fame. Everyone knows me; they’ve all heard my name. The world won’t recognize Berwick, Salem, Peach Bottom, or the place near Springfield (not the one with the donut-eating man who drools when he sleeps on the job, the real one in Montgomery County, Pennsylvania). Oyster Creek, Beaver Valley, Hope Creek, and dozens of others won’t ring a bell, but they’ll recall me with emotion or story, and often with myth as well—I’m a Nuclear Star.

I’m the ultimate thriller, generating anxiety from day one. My worldwide debut was the stuff of legend; you saw me on the news. You remember all the dramatic tension, don’t you? Like all celebrities, I blew off a little steam, had a little gas, and then everyone waited, trying to figure out what was going to happen next. But I kept things under wraps, shrouded in a fog of mystery, not a sole eyewitness to the events in my inner sanctum. Confusion reigned. There was a sense of great danger and imminent catastrophe. There prevailed a sweaty uncertainty over the threat of disaster and invisible death.

Would I melt down?

Would I blow my top?

Those iconic and sinister towers, what kind of horrid poisons pour from them to burn the sky and land?

The world needed to know. People demanded information.

Well, I know your trust in me was eroded and you felt deceived by my agents. You saw it, how they withered in the spotlight of fame while trying to protect themselves and the new Nuclear Star. The uncertainty they caused motivated many of my neighbors to leave. Many more were pushed beyond rational skepticism about me to an enduring cynicism which persists to this day. Fortunately, a genuine, competent, straight-talking communicator arrived to allay everyone’s fears with frank and understandable explanations of the situation. Then, a visit by the President of the United States assuaged the trepidations of a frightened public and provided reassurance to those who left that it was safe to return.

I want everyone to know that I had plans for a long quiet career. Then, three months into it, a handler pressed my buttons the wrong way and I’ve been in the limelight ever since. I did melt down a bit, but thanks to a timely intervention, I didn’t drop through the floor. For the same reason, I didn’t go through the roof either. You need to know that I’m no bomb. I was built to last for the long haul, and I won’t go to pieces. Remember, I’m a Nuclear Star. Oh, and those really are just big fluffy white steam clouds coming out of those towers, nothing more. It’s true.

I’m really not so scary. There’s no scheming evil little man hiding in my shadow planning the demise of the planet. Only the flies sit around rubbing their tiny hands together as they contemplate their next move, and I’ll remind you that not even one of them was hurt here.

I’m a Nuclear Star; my legacy is secured. Come look at me and feel the awe. After all these years, I continue to make nervous those who see me in person. You’ll still see the crowds and cameras outside my gates from time to time, demanding to know what kind of devious scheme is being hatched inside. I remain a central figure, but typecast as the villain. Without fail, I’m presumed to be the deleterious factor when man or nature ails. It’s not the coal-choker down the river, or the dam wall next door. It’s not the smoldering trash cookers north and south, or the sludge on the fields. It’s not the junk mixed into the food, or the spraying willy-nilly. Nor is it the filth in the water, the lazy life, or the smog in the city. It’s not the cigarette in your mouth, the synthetics in your house, the hours in your car. It’s Three Mile Island. That’s what did it. I’m a Nuclear Star.

Three Mile Island Nuclear Generating Station. Unit 2 (left) has been shut down since the March 28, 1979 accident and partial meltdown. Unit 1 (right) is currently operating and producing electricity.

Oh, and by the way, the plant in Montgomery County is called Limerick, in case you were wondering.

January 14, 2018July 1, 2018

Essential Ice

Two days ago, widespread rain fell intermittently through the day and steadily into the night in the Susquehanna drainage basin. The temperature was sixty degrees, climbing out of a three-week-long spell of sub-freezing cold in a dramatic way. Above the ice-covered river, a very localized fog swirled in the southerly breezes.

By yesterday, the rain had ended as light snow and a stiff wind from the northwest brought sub-freezing air back to the region. Though less than an inch of rain fell during this event, much of it drained to waterways from frozen or saturated ground. Streams throughout the watershed are being pushed clear of ice as minor flooding lifts and breaks the solid sheets into floating chunks.

Today, as their high flows recede, the smaller creeks and runs are beginning to freeze once again. On larger streams, ice is still exiting with the cresting flows and entering the rising river.

Ice chunks on Swatara Creek merge into a dense flow of ice on the river in the distance. Swatara Creek is the largest tributary to enter the Susquehanna in the Gettysburg Basin. The risk of an ice jam impounding the Swatara here at its mouth is lessened because rising water on the river has lifted and broken the ice pack to keep it moving without serious impingement by submerged obstacles. Immovable ice jams on the river can easily block the outflow from tributaries, resulting in catastrophic flooding along these streams.

Fast-moving flows of jagged ice race toward Three Mile Island and Conewago Falls. The rising water began relieving the compression of ice along the shoreline during the mid-morning. Here on the river just downstream of the mouth of Swatara Creek, ice-free openings allowed near-shore piles to separate and begin floating away after 10:30 A.M. E.S.T. Moving masses of ice created loud rumbles, sounding like a distant thunderstorm.

Ice being pushed and heaved over the crest of the York Haven Dam at Conewago Falls due to compression and rising water levels.

Enormous chunks of ice being forced up and over the York Haven Dam into Conewago Falls and the Pothole Rocks below.

Ice scours Conewago Falls, as it has for thousands of years.

The action of ice and suspended abrasives has carved the York Haven Diabase boulders and bedrock of Conewago Falls into the amazing Pothole Rocks.

The roaring torrents of ice-choked water will clear some of the woody growth from the Riverine Grasslands of Conewago Falls.

To the right of center in this image, a motorcar-sized chunk of ice tumbles over the dam and crashes into the Pothole Rocks. It was one of thousands of similar tree-and-shrub-clearing projectiles to go through the falls today.

The events of today provide a superb snapshot of how Conewago Falls, particularly the Diabase Pothole Rocks, became such a unique place, thousands of years in the making. Ice and flood events of varying intensity, duration, and composition have sculpted these geomorphologic features and contributed to the creation of the specialized plant and animal communities we find there. Their periodic occurrence is essential to maintaining the uncommon habitats in which these communities thrive.

Fish Crows *(Corvus ossifragus)* gather along the flooding river shoreline. Soon there’ll be plenty of rubbish to pick through, some carrion maybe, or even a displaced aquatic creature or two to snack upon.

January 1, 2018January 2, 2018

Eighteen, and I Like It

Is this the same Conewago Falls I visited a week ago? Could it really be? Where are all the gulls, the herons, the tiny critters swimming in the potholes, and the leaping fish? Except for a Bald Eagle on a nearby perch, the falls seems inanimate.

Yes, a week of deep freeze has stifled the Susquehanna and much of Conewago Falls. A hike up into the area where the falls churns with great turbulence provided a view of some open water. And a flow of open water is found downstream of the York Haven Dam powerhouse discharge. All else is icing over and freezing solid. The flow of the river pinned beneath is already beginning to heave the flat sheets into piles of jagged ice which accumulate behind obstacles and shallows.

Ice and snow surround a small zone of open water in a high-gradient area of Conewago Falls.

Ice chunks and sheets accumulate atop the York Haven Dam. The weight of miles of ice backed up behind the dam eventually forces the accumulation over the top and into the Pothole Rocks below. The popping and cracking sounds of ice both above and below the dam could be heard throughout the day as hydraulic forces continuously break and move ice sheets.

Steam from the Unit 1 cooling towers at the Three Mile Island Nuclear Generating Station rises above the frozen Riverine Grasslands at Conewago Falls. The scouring action of winter ice keeps the grasslands clear of substantial woody growth and prevents succession into forest.

Despite a lack of activity on the river, mixed flocks of resident and wintering birds, including this White-breasted Nuthatch *(Sitta carolinensis)*, were busy feeding in the Riparian Woodlands. The White-breasted Nuthatch is a cavity nester and year-round denizen of hardwoods, often finding shelter during harsh winter nights in small tree holes.

The White-breasted Nuthatch is often seen working its way head-first down a tree trunk as it probes with its well-adapted bill for insects among the bark.

Looking upstream from the river’s east shore at ice and snow cover on the Susquehanna above Conewago Falls and the York Haven Dam. The impoundment, known as Lake Frederic, and its numerous islands of the Gettysburg Basin Archipelago were locked in winter’s frosty grip today. Hill Island (Left) and Poplar Island (Center) consist of erosion-resistant York Haven Diabase, as does the ridge on the far shoreline seen rising in the distance between them. To the right of Poplar Island in this image, the river passes by the Harrisburg International Airport. At the weather station there, the high temperature was eighteen degrees Fahrenheit on this first day of 2018.

July 18, 2017March 30, 2024

The Wall

It was one of the very first of my memories. From the lawn of our home I could look across the road and down the hill through a gap in the woodlands. There I could see water, sometimes still with numerous boulders exposed, other times rushing, muddy, and roaring. Behind these waters was a great stone wall and beyond that a wooded hillside. I recall my dad asking me if I could see the dam down there. I couldn’t see a dam, just fascinating water and the gray wall behind it. I looked and searched but not a trace of a structure spanning the near to far shore was to be seen. Finally, at some point, I answered in the affirmative to his query; I could see the dam…but I couldn’t.

We lived in a small house in the village of Falmouth along the Susquehanna River in the northwest corner of Lancaster County over fifty years ago. A few years after we had left our riverside domicile and moved to a larger town, the little house was relocated to make way for an electric distribution sub-station and a second set of electric transmission wires in the gap in the woodlands. The Brunner Island coal-fired electric generating station was being upgraded downstream and, just upstream, a new nuclear-powered generating station was being constructed on Three Mile Island. To make way for the expanding energy grid, our former residence was trucked to a nearby boat landing where there were numerous other river shacks and cabins. Because it was placed in the floodplain, the building was raised onto a set of wooden stilts to escape high water. It didn’t help. The record-breaking floods of Hurricane Agnes in June of 1972 swept the house away.

The view through the cut in the woodland, a little wider than in the early 1960s with the addition of the newer electric transmission wire towers. The “Wall” is the same.

During the time we lived along the Susquehanna, the river experienced record-low flow rates, particularly in the autumn of 1963 and again in 1964. My dad was a dedicated 8mm home-movie photographer. Among his reels was film of buses parked haphazardly along the road (PA Route 441 today) near our home. Sightseers were coming to explore the widely publicized dry riverbed and a curious moon-like landscape of cratered rocks and boulders. It’s hard to fathom, but people did things like that during their weekends before Sunday-afternoon football was invented. Scores of visitors climbed through the rocks and truck-size boulders inspecting this peculiar scene. My dad, his friends, and so many others with camera in hand were experiencing the amazing geological feature known as the Pothole Rocks of Conewago Falls.

Conewago Falls on the Susquehanna River and several exposed York Haven Diabase Pothole Rocks. Lancaster (foreground) and Dauphin (center) Counties meet along a southwest to northeast borderline through the rapids. Lands on the west shoreline in the background are in York County. Three Mile Island is seen in the upper right.

The river here meets serious resistance as it pushes its way through the complex geology of south-central Pennsylvania. These hard dark-gray rocks, York Haven Diabase, are igneous in origin. Diabase sheets and sills intruded the Triassic sediments of the Gettysburg Formation here over 190 million years ago. It may be difficult to visualize, but these sediments were eroded from surrounding mountains into the opening rift valley we call the Gettysburg Basin. This rift and others in a line from Nova Scotia to Georgia formed as the supercontinent Pangaea began dividing into the continents we know today. Eventually the Atlantic Ocean rift would dominate as the active dynamic force and open to separate Africa from North America. The inactive Gettysburg Basin, filled with sediments and intruded by igneous diabase, would henceforth, like the mountainous highlands surrounding it, be subjected to millions of years of erosion. Of the regional rocks, the formations of Triassic redbeds, sandstones, and particularly diabase in the Gettysburg Basin are among the more resistant to the forces of erosion. Many less resistant older rocks, particularly those of surrounding mountains, are gone. Today, the remains of the Gettysburg Basin’s rock formations stand as rolling highlands in the Piedmont Province.

Flooded from the heavy rains of Tropical Storm Lee, the sediment-laden Susquehanna River flows through the Gettysburg Basin just south of Harrisburg, PA, September 10, 2011. The “Wall” as seen from space. (NASA Earth Observatory Image)

The weekend visitors in 1963 and 1964 marveled at evidence of the river’s fight to break down the hard York Haven Diabase. Scoured bedrock traced the water’s turbulent flow patterns through the topography of the falls. Meltwater from the receding glaciers of the Pleistocene Ice Ages thousands to tens of thousands of years ago raged in high-volume, abrasive-loaded torrents to sculpt the Pothole Rocks into the forms we see today. Our modern floodwaters with ice and fine suspended sediments continue to wear at the smooth rocks and boulders, yet few are broken or crumbled to be swept away. It’s a very slow process. The river elevation here drops approximately 19 feet in a quarter of a mile, a testament to the bedrock’s persisting resistance to erosion. Conewago Falls stands as a natural anomaly on a predominantly uniform gradient along the lower Susquehanna’s downhill path from the Appalachian Mountains to the Chesapeake Bay.

Normally the scene of dangerous tumbling rapids, the drought and low water of 1963 and 1964 had left the falls to resemble a placid scene—a moonscape during a time when people were obsessed with mankind’s effort to visit earth’s satellite. Visitors saw the falls as few others had during the twentieth century. Dr. Herbert Beck of Franklin and Marshall College described an earlier period of exposure, “…pot holes…were uncovered during the third week in October, 1947, for the first time in the memory of man, when the drought parched Susquehanna River retreated far below its normal low stage”. Then, as in 1963 and on occasions more recent, much of it was due to the presence of the wall. I had to be a bit older than four years old to grasp it. You see the wall and the dam are one and the same. The wall is the York Haven Dam. And it is responsible for channeling away the low flow of the Susquehanna during periods of drought so that we might have the opportunity to visit and explore the Pothole Rocks of Conewago Falls along the river’s east shore.

The initial segment of the dam, a crib structure built in 1885 by the York Haven Paper Company to supply water power to their mill, took advantage of the geomorphic features of the diabase bedrock of Conewago Falls to divert additional river flow into the abandoned Conewago Canal. The former canal, opened in 1797 to allow passage around the rapids along the west shore, was being used as a headrace to channel water into the grinding mill’s turbines. Strategic placement of this first wall directed as much water as possible toward the mill with the smallest dam practicable. The York Haven Power Company incorporated the paper mill’s crib dam into the “run-of-the-river” dam built through the falls from the electric turbine powerhouse they constructed on the west shore to the southern portion of Three Mile Island more than a mile away. The facility began electric generation in 1904. The construction of the “Red Hill Dam” from the east shore of Three Mile Island to the river’s east shore made York Haven Dam a complete impoundment on the Susquehanna. The pool, “Lake Frederic”, thus floods that portion of the Pothole Rocks of Conewago Falls located behind the dam. On the downstream side, water spilling over or through the dam often inundates the rocks or renders them inaccessible.

During the droughts of the early 1960s, diversion of nearly all river flow to the York Haven Dam powerhouse cleared the way for weekend explorers to see the Pothole Rocks in detail. Void of water, the intriguing bedrock of Conewago Falls below the dam greeted the curious with its ripples, cavities, and oddity. It was an opportunity nature alone would not provide. It was all because of the wall.

York Haven Dam and powerhouse. The “Wall” traverses Conewago Falls upstream to Three Mile Island to direct water to the powerhouse on the west shore of the Susquehanna River.

SOURCES

Beck, Herbert H. 1948. “The Pot Holes of Conewago Falls”. Proceedings of the Pennsylvania Academy of Science. Penn State University Press. 22: pp. 127-130.

Smith, Stephen H. 2015. #6 York Haven Paper Company; on the Site of One of the Earliest Canals in America. York Past website www.yorkblog.com/yorkpast/2015/02/17/6-york-haven-paper-company-on-the-site-of-one-of-the-earliest-canals-in-america/ as accessed July 17, 2017.

Stranahan, Susan Q. 1993. Susquehanna, River of Dreams. The Johns Hopkins University Press. Baltimore, Maryland.

Van Diver, Bradford B. 1990. Roadside Geology of Pennsylvania. Mountain Press Publishing Company. Missoula, Montana.