At this very moment, your editor is comfortably numb and is, if everything is going according to plans, again having a snake run through the plumbing in his body’s most important muscle. It thus occurs to him how strange it is that with muscles as run down and faulty as his, people at one time asked him to come speak about and display his marvelous mussels. And some, believe it or not, actually took interest in such a thing. If the reader finds this odd, he or she would not be alone. But the peculiarities don’t stop there. The reader may find further bewilderment after being informed that the editor’s mussels are now in the collection of a regional museum where they are preserved for study by qualified persons with scientific proclivities. All of this show and tell was for just one purpose—to raise appreciation and sentiment for our mussels, so that they might be protected.
Click on the “Freshwater Mussels and Clams” tab at the top of this page to see the editor’s mussels, and many others as well. Then maybe you too will want to flex your muscles for our mussels. They really do need, and deserve, our help.
The Pennsylvania Department of Environmental Protection has issued a “drought watch” for much of the state’s Susquehanna basin including Dauphin, Lebanon, and Perry Counties—plus those counties to their north. Residents are asked to conserve water in the affected areas.
Water conservation measures are voluntary during a drought watch, and most consumers try to cut back on nonessential use. For many though, threats to water supply and water quality generate little concern. This evening, on this farm along a Dauphin County waterway undergoing restoration, we shouldn’t be too surprised to see lots of water being pumped from the creek to soak down liquid manure that was spread on the fields earlier in the week. This happens to be the only property along a five-mile segment of stream that still allows cattle and draft horses to wade, defecate, and urinate in the water. It is the only parcel for nearly seven miles that has eroding banks of legacy sediments that are maintained denuded of nearly all vegetation. Despite some beneficial practices like the use of cover crops, it’s a polluter. And now its operator appears to be engaged in something new: “stream dewatering”. With three irrigation guns in operation, this farmer was easily pumping and removing up to one half or more of the creek’s flow, which at the time, according to a United States Geological Survey gauge less than a mile upstream, was only about 3 cubic feet per second or 1,100 gallons per minute (G.P.M.). That doesn’t let much for the municipalities downstream that rely upon this waterway as a supplemental source of drinking water, does it? Such a large reduction in base flow can threaten the survival of fish and other aquatic inhabitants in the creek, particular during hot summer weather when dissolved oxygen levels can be at their lowest of the year. Water is like a lot of other necessities, no one really gives it a second thought until they don’t have it; and as long as I have mine, that’s all that really matters.
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.
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)1972- In this close-up of the preceding photo, the aforementioned piles of junk can be seen along the upstream side of the bridge (behind the sign on the right). The fuel tank struck and was rolling on the far side of this pile. (Larry L. Coble, Sr. image)2022- Three Mile Island’s “south bridge” as it appeared this morning, June 24,2022.1972- The railroad along the east shore at Three Mile Island’s “south bridge” was inundated by rising water. This flooded automobile was one of many found in the vicinity. Some of these vehicles were overtaken by rising water while parked, others were stranded while being driven, and still others floated in from points unknown. (Larry L. Coble, Sr. image)2022- A modern view of the same location.1972- At the north end of Three Mile Island, construction on Unit 1 was halted. The completed cooling towers can be seen to the right and the round reactor building can be seen behind the generator building to the left. The railroad grade along the river’s eastern shore opposite the north end of the island was elevated enough for this train to stop and shelter there for the duration of the flood. (Larry L. Coble, Sr. image)2022- Three Mile Island Unit 1 as it appears today: shut down, defueled, and in the process of deconstruction.1972- In March of 1979, the world would come to know of Three Mile Island Unit 2. During Agnes in June of 1972, flood waters surrounding the plant resulted in a delay of its construction. In the foreground, note the boxcar from the now defunct Penn Central Railroad. (Larry L. Coble, Sr. image)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.
The remnants of Hurricane Ida are on their way to the Lower Susquehanna River Watershed. After making landfall in Louisiana as a category 4 storm, Ida is on track to bring heavy rain to the Mid-Atlantic States beginning tonight.
Tropical Depression Ida moving slowly toward the northeast. (NOAA/GOES image)
Rainfall totals are anticipated to be sufficient to cause flooding in the lower Susquehanna basin. As much as six to ten inches of precipitation could fall in parts of the area on Wednesday.
Rainfall forecasts from the National Hurricane Center. (NOAA/National Hurricane Center image)
Now would be a good time to get all your valuables and junk out of the floodways and floodplains. Move your cars, trucks, S.U.V.s, trailers, and boats to higher ground. Clear out the trash cans, playground equipment, picnic tables, and lawn furniture too. Get it all to higher ground. Don’t be the slob who uses a flood as a chance to get rid of tires and other rubbish by letting it just wash away.
Vehicles parked atop fill that has been dumped into a stream’s floodplain are in double trouble. Fill displaces water and exasperates flooding instead of providing refuge from it. Better move these cars, trucks, and trailers to higher ground, posthaste.
Flooding not only has economic and public safety impacts, it is a source of enormous amounts of pollution. Chemical spills from inundated homes, businesses, and vehicles combine with nutrient and sediment runoff from eroding fields to create a filthy brown torrent that rushes down stream courses and into the Susquehanna. Failed and flooded sewage facilities, both municipal and private, not only pollute the water, but give it that foul odor familiar to those who visit the shores of the river after a major storm. And of course there is the garbage. The tons and tons of waste that people discard carelessly that, during a flood event, finds its way ever closer to the Susquehanna, then the Chesapeake, and finally the Atlantic. It’s a disgraceful legacy.
Now is your chance to do something about it. Go out right now and pick up the trash along the curb, in the street, and on the sidewalk and lawn—before it gets swept into your nearby stormwater inlet or stream. It’s easy to do, just bend and stoop. While you’re at it, clean up the driveway and parking lot too.
Secure your trash and pick up litter before it finds its way into the storm sewer system and eventually your local stream. It’ll take just a minute.This is how straws and other plastics find their way to the ocean and the marine animals living there, so pick that stuff up! Did you know that keeping stormwater inlets clean can prevent street flooding and its destructive extension into the cellars of nearby homes and businesses?There’s another straw. Pick it and the rest of that junk up now, before the storm. Don’t wait for your local municipality or the Boy Scouts to do it. You do it, even if it’s not your trash.
We’ll be checking to see how you did.
And remember, flood plains are for flooding, so get out of the floodplain and stay out.
You say you really don’t want to take a look back at 2020? Okay, we understand. But here’s something you may find interesting, and it has to do with the Susquehanna River in 2020.
As you may know, the National Weather Service has calculated the mean temperature for the year 2020 as monitored just upriver from Conewago Falls at Harrisburg International Airport. The 56.7° Fahrenheit value was the highest in nearly 130 years of monitoring at the various stations used to register official climate statistics for the capital city. The previous high, 56.6°, was set in 1998.
Though not a prerequisite for its occurrence, record-breaking heat was accompanied by a drought in 2020. Most of the Susquehanna River drainage basin experienced drought conditions during the second half of the year, particularly areas of the watershed upstream of Conewago Falls. A lack of significant rainfall resulted in low river flows throughout late summer and much of the autumn. Lacking water from the northern reaches, we see mid-river rocks and experience minimal readings on flow gauges along the lower Susquehanna, even if our local precipitation happens to be about average.
Back in October, when the river was about as low as it was going to get, we took a walk across the Susquehanna at Columbia-Wrightsville atop the Route 462/Veteran’s Memorial Bridge to have a look at the benthos—the life on the river’s bottom.
As we begin our stroll across the river, we quickly notice Mallards and a Double-crested Cormorant (far left) feeding among aquatic plants. You can see the leaves of the vegetation just breaking the water’s surface, particularly behind the feeding waterfowl. Let’s have a closer look.An underwater meadow of American Eelgrass (Vallisneria americana) as seen from atop the Veteran’s Memorial Bridge at Columbia-Wrightsville. Also known as Freshwater Eelgrass, Tapegrass, and Wild Celery, it is without a doubt the Susquehanna’s most important submerged aquatic plant. It grows in alluvial substrate (gravel, sand, mud, etc.) in river segments with moderate to slow current. Water three to six feet deep in bright sunshine is ideal for its growth, so an absence of flooding and the sun-blocking turbidity of muddy silt-laden water is favorable.Plants in the genus Vallisneria have ribbon-like leaves up to three feet in length that grow from nodes rooted along the creeping stems called runners. A single plant can, over a period of years, spread by runners to create a sizable clump or intertwine with other individual plants to establish dense meadows and an essential wildlife habitat.An uprooted segment of eelgrass floats over a thick bed of what may be parts of the same plant. Eelgrass meadows on the lower Susquehanna River were decimated by several events: deposition of anthracite coal sediments (culm) in the late-nineteenth and early-twentieth centuries, dredging of the same anthracite coal sediments during the mid-twentieth century, and the ongoing deposition of sediments from erosion occurring in farm fields, logged forests, abandoned mill ponds, and along denuded streambanks. Not only has each of these events impacted the plants physically by either burying them or ripping them out by the roots, each has also contributed to the increase in water turbidity (cloudiness) that blocks sunlight and impairs their growth and recovery.A submerged log surrounded by beds of eelgrass forms a haven for fishes in sections of the river lacking the structure found in rock-rich places like Conewago Falls. A period absent of high water and sediment runoff extended through the growing season in 2020 to allow lush clumps of eelgrass like these to thrive and further improve water quality by taking up nutrients, particularly nitrogen and phosphorus. Nutrients used by vascular plants including eelgrass become unavailable for feeding detrimental algal blooms in downstream waters including Chesapeake Bay.Small fishes and invertebrates attract predatory fishes to eelgrass beds. We watched this Smallmouth Bass leave an ambush site among eelgrass’s lush growth to shadow a Common Carp as it rummaged through the substrate for small bits of food. The bass would snatch up crayfish that darted away from the cover of stones disturbed by the foraging carp.Sunfishes are among the species taking advantage of eelgrass beds for spawning. They’ll build a nest scrape in the margins between clumps of plants allowing their young quick access to dense cover upon hatching. The abundance of invertebrate life among the leaves of eelgrass nourishes feeding fishes, and in turn provides food for predators including Bald Eagles, this one carrying a freshly-caught Bluegill.
These improvements in water quality and wildlife habitat can have a ripple effect. In 2020, the reduction in nutrient loads entering Chesapeake Bay from the low-flowing Susquehanna may have combined with better-than-average flows from some of the bay’s lesser-polluted smaller tributaries to yield a reduction in the size of the bay’s oxygen-deprived “dead zones”. These dead zones typically occur in late summer when water temperatures are at their warmest, dissolved oxygen levels are at their lowest, and nutrient-fed algal blooms have peaked and died. Algal blooms can self-enhance their severity by clouding water, which blocks sunlight from reaching submerged aquatic plants and stunts their growth—making quantities of unconsumed nutrients available to make more algae. When a huge biomass of algae dies in a susceptible part of the bay, its decay can consume enough of the remaining dissolved oxygen to kill aquatic organisms and create a “dead zone”. The Chesapeake Bay Program reports that the average size of this year’s dead zone was 1.0 cubic miles, just below the 35-year average of 1.2 cubic miles.
Back on a stormy day in mid-November, 2020, we took a look at the tidal freshwater section of Chesapeake Bay, the area known as Susquehanna Flats, located just to the southwest of the river’s mouth at Havre de Grace, Maryland. We wanted to see how the restored American Eelgrass beds there might have fared during a growing season with below average loads of nutrients and life-choking sediments spilling out of the nearby Susquehanna River. Here’s what we saw.
We followed the signs from Havre de Grace to Swan Harbor Farm Park.Harford County Parks and Recreation’s Swan Harbor Farm Park consists of a recently-acquired farming estate overlooking the tidal freshwater of Susquehanna Flats.Along the bay shore, a gazebo and a fishing pier have been added. Both provide excellent observation points.The shoreline looked the way it should look on upper Chesapeake Bay, a vegetated buffer and piles of trees and other organic matter at the high-water line. There was less man-made garbage than we might find following a summer that experienced an outflow from river flooding, but there was still more than we should be seeing.Judging by the piles of fresh American Eelgrass on the beach, it looks like it’s been a good year. Though considered a freshwater plant, eelgrass will tolerate some brackish water, which typically invades upper Chesapeake Bay each autumn due to a seasonal reduction in freshwater inflow from the Susquehanna and other tributaries. Saltwater can creep still further north when the freshwater input falls below seasonal norms during years of severe drought. The Susquehanna Flats portion of the upper bay very rarely experiences an invasion by brackish water; there was none in 2020.As we scanned the area with binoculars and a spotting scope, a raft of over one thousand ducks and American Coots (foreground) could be seen bobbing among floating eelgrass leaves and clumps of the plants that had broken away from their mooring in the mud. Waterfowl feed on eelgrass leaves and on the isopods and other invertebrates that make this plant community their home.While coots and grebes seemed to favor the shallower water near shore, a wide variety of both diving and dabbling ducks were widespread in the eelgrass beds more distant. Discernable were Ring-necked Ducks, scaup, scoters, Long-tailed Ducks, Redheads, American Wigeons, Gadwall, Ruddy Ducks, American Black Ducks, and Buffleheads.
We noticed a few Canvasbacks (Aythya valisineria) on the Susquehanna Flats during our visit. Canvasbacks are renowned as benthic feeders, preferring the tubers and other parts of submerged aquatic plants (a.k.a. submersed aquatic vegetation or S.A.V.) including eelgrass, but also feeding on invertebrates including bivalves. The association between Canvasbacks and eelgrass is reflected in the former’s scientific species name valisineria, a derivitive of the genus name of the latter, Vallisneria.
Canvasbacks on Chesapeake Bay. (United States Fish and Wildlife Service image by Ryan Hagerty)
The plight of the Canvasback and of American Eelgrass on the Susquehanna River was described by Herbert H. Beck in his account of the birds found in Lancaster County, Pennsylvania, published in 1924:
“Like all ducks, however, it stops to feed within the county less frequently than formerly, principally because the vast beds of wild celery which existed earlier on broads of the Susquehanna, as at Marietta and Washington Borough, have now been almost entirely wiped out by sedimentation of culm (anthracite coal waste). Prior to 1875 the four or five square miles of quiet water off Marietta were often as abundantly spread with wild fowl as the Susquehanna Flats are now.”
Beck quotes old Marietta resident and gunner Henry Zink:
“Sometimes there were as many as 500,000 ducks of various kinds on the Marietta broad at one time.”
The abundance of Canvasbacks and other ducks on the Susquehanna Flats would eventually plummet too. In the 1950s, there were an estimated 250, 000 Canvasbacks wintering on Chesapeake Bay, primarily in the area of the American Eelgrass, a.k.a. Wild Celery, beds on the Susquehanna Flats. When those eelgrass beds started disappearing during the second half of the twentieth century, the numbers of Canvasbacks wintering on the bay took a nosedive. As a population, the birds moved elsewhere to feed on different sources of food, often in saltier estuarine waters.
Canvasbacks were able to eat other foods and change their winter range to adapt to the loss of habitat on the Susquehanna River and Chesapeake Bay. But not all species are the omnivores that Canvasbacks happen to be, so they can’t just change their diet and/or fly away to a better place. And every time a habitat like the American Eelgrass plant community is eliminated from a region, it fragments the range for each species that relied upon it for all or part of its life cycle. Wildlife species get compacted into smaller and smaller suitable spaces and eventually their abundance and diversity are impacted. We sometimes marvel at large concentrations of birds and other wildlife without seeing the whole picture—that man has compressed them into ever-shrinking pieces of habitat that are but a fraction of the widespread environs they once utilized for survival. Then we sometimes harass and persecute them on the little pieces of refuge that remain. It’s not very nice, is it?
By the end of 2020, things on the Susquehanna were getting back to normal. Near normal rainfall over much of the watershed during the final three months of the year was supplemented by a mid-December snowstorm, then heavy downpours on Christmas Eve melted it all away. Several days later, the Susquehanna River was bank full and dishing out some minor flooding for the first time since early May. Isn’t it great to get back to normal?
The rain-and-snow-melt-swollen Susquehanna from Chickies Rock looking upriver toward Marietta during the high-water crest on December 27th.Cresting at Columbia as seen from the Route 462/Veteran’s Memorial Bridge. A Great Black-backed Gull monitors the waters for edibles.All back to normal on the Susquehanna to end 2020.Yep, back to normal on the Susquehanna. Maybe 2021 will turn out to be another good year, or maybe it’ll just be a Michelin or Firestone.
SOURCES
Beck, Herbert H. 1924. A Chapter on the Ornithology of Lancaster County, Pennsylvania. The Lewis Historical Publishing Company. New York, NY.
White, Christopher P. 1989. Chesapeake Bay, Nature of the Estuary: A Field Guide. Tidewater Publishers. Centreville, MD.
It was a routine occurrence in many communities along tributaries of the lower Susquehanna River during the most recent two months. The rain falls like it’s never going to stop—inches an hour. Soon there is flash flooding along creeks and streams. Roads are quickly inundated. Inevitably, there are motorists caught in the rising waters and emergency crews are summoned to retrieve the victims. When the action settles, sets of saw horses are brought to the scene to barricade the road until waters recede. At certain flood-prone locations, these events are repeated time and again. The police, fire, and Emergency Medical Services crews seem to visit them during every torrential storm—rain, rescue, rinse, and repeat.
We treat our local streams and creeks like open sewers. Think about it. We don’t want rainwater accumulating on our properties. We pipe it away and grade the field, lawn, and pavement to roll it into the neighbor’s lot or into the street—or directly into the waterway. It drops upon us as pure water and we instantly pollute it. It’s a method of diluting all the junk we’ve spread out in its path since the last time it rained. A thunderstorm is the big flush. We don’t seem too concerned about the litter, fertilizer, pesticides, motor fluids, and other consumer waste it takes along with it. Out of sight, out of mind.
Failure to retain and infiltrate stormwater to recharge aquifers can later result in well failures and reduced base flow in streams. (Conoy Creek’s dry streambed in June, 2007)
Perhaps our lack of respect for streams and creeks is the source of our complete ignorance of the function of floodplains.
Floodplains are formed over time as hydraulic forces erode bedrock and soils surrounding a stream to create adequate space to pass flood waters. As floodplains mature they become large enough to reduce flood water velocity and erosion energy. They then function to retain, infiltrate, and evaporate the surplus water from flood events. Microorganisms, plants, and other life forms found in floodplain wetlands, forests, and grasslands purify the water and break down naturally-occurring organic matter. Floodplains are the shock-absorber between us and our waterways. And they’re our largest water treatment facilities.
Why is it then, that whenever a floodplain floods, we seem motivated to do something to fix this error of nature? Man can’t help himself. He has a compulsion to fill the floodplain with any contrivance he can come up with. We dump, pile, fill, pave, pour, form, and build, then build some more. At some point, someone notices a stream in the midst of our new creation. Now it’s polluted and whenever it storms, the darn thing floods into our stuff—worse than ever before. So the project is crowned by another round of dumping, forming, pouring, and building to channelize the stream. Done! Now let’s move all our stuff into our new habitable space.
Natural Floodplain- Over a period of hundreds or thousands of years, the stream (dark blue) has established a natural floodplain including wetlands and forest. In this example, buildings and infrastructure are located outside the zone inundated by high water (light blue) allowing the floodplain to function as an effective water-absorbing buffer.Impaired Floodplain- Here the natural floodplain has been filled for building (left) and paved for recreation area parking (right). The stream has been channelized. Flood water (light blue) displaced by these alterations is likely to inundate areas not previously impacted by similar events. Additionally, the interference with natural flow will create new erosion points that could seriously damage older infrastructure and properties.
The majority of the towns in the lower Susquehanna valley with streams passing through them have impaired floodplains. In many, the older sections of the town are built on filled floodplain. Some new subdivisions highlight streamside lawns as a sales feature—plenty of room for stockpiling your accoutrements of suburban life. And yes, some new homes are still being built in floodplains.
When high water comes, it drags tons of debris with it. The limbs, leaves, twigs, and trees are broken down by natural processes over time. Nature has mechanisms to quickly cope with these organics. Man’s consumer rubbish is another matter. As the plant material decays, the embedded man-made items, particularly metals, treated lumber, plastics, Styrofoam, and glass, become more evident as an ever-accumulating “garbage soil” in the natural floodplains downstream of these impaired areas. With each storm, some of this mess floats away again to move ever closer to Chesapeake Bay and the Atlantic. Are you following me? That’s our junk from the curb, lawn, highway, or parking lot bobbing around in the world’s oceans.
A shed, mobile home, or house can be inundated or swept away during a flood. Everything inside (household chemicals, gasoline, fuel oil, pesticides, insulation, all those plastics, etc.) instantly pollutes the water. Many communities that rely on the Susquehanna River for drinking water are immediately impacted, including Lancaster, PA and Baltimore, MD. This dumpster was swept away from a parking lot in a floodplain. It rolled in the current, chipping away at the bridge before spilling the rubbish into the muddy water. After the flood receded, the dumpster was found a mile downstream. Its contents are still out there somewhere.Floodplains along the lower Susquehanna River are blanketed with a layer of flotsam that settles in place as high water recedes. These fresh piles can be several feet deep and stretch for miles. Nature decomposes the organic twigs and driftwood to build soil-enriching humus. However, the plastics and other man-made materials that do not readily decay or do not float away toward the sea during the next flood are incorporated into the alluvium and humus creating a “garbage soil”. Over time, the action of abrasives in the soil will grind small particles of plastics from the larger pieces. These tiny plastics can become suspended in the water column each time the river floods. What will be the long-term impact of this type of pollution?Anything can be swept away by the powerful hydraulic forces of flowing water. Large objects like this utility trailer can block passages through bridges and escalate flooding problems.The cost of removing debris often falls upon local government and is shared by taxpayers.Here, a junked boat dock is snagged on the crest of the York Haven Dam at Conewago Falls. Rising water eventually carried it over the dam and into the falls where it broke up. This and tons of other junk are often removed downstream at the Safe Harbor Dam to prevent damage to turbine equipment. During periods of high water, the utility hauls debris by the truck-load to the local waste authority for disposal. For the owners of garbage like this dock, it’s gone and it’s somebody else’s problem now.Motor vehicles found after floating away from parking areas in floodplains can create a dangerous dilemma for police, fire, and E.M.S. personnel, particularly when no one witnesses the event. Was someone driving this car or was it vacant when it was swept downstream? Should crews be put at risk to locate possible victims?
Beginning in 1968, participating municipalities, in exchange for having coverage provided to their qualified residents under the National Flood Insurance Program, were required to adopt and enforce a floodplain management ordinance. The program was intended to reduce flood damage and provide flood assistance funded with premiums paid by potential victims. The program now operates with a debt incurred during severe hurricanes. Occurrences of repetitive damage claims and accusations that the program provides an incentive for rebuilding in floodplains have made the National Flood Insurance Program controversial.
In the Lower Susquehanna River Watershed there are municipalities that still permit new construction in floodplains. Others are quite proactive at eliminating new construction in flood-prone zones, and some are working to have buildings removed that are subjected to repeated flooding.
Another Wall— Here’s an example of greed by the owner, engineer, and municipality… placing their financial interests first. The entire floodplain on the north side of this stream was filled, then the wall was erected to contain the material. A financial institution’s office and parking lot was constructed atop the mound. This project has channelized the stream and completely displaced half of the floodplain to a height of 15 to 20 feet. Constructed less than five years ago, the wall failed already and has just been totally reconstructed. The photo reveals how recent flooding has begun a new erosion regime where energy is focused along the base of the wall. Impairment of a floodplain to this degree can lead to flooding upstream of the site and erosion damage to neighboring infrastructure including roads and bridges.The floodplain along this segment of the lower Swatara Creek in Londonderry Township, Dauphin County is free to flood. Ordinances prohibit new construction here and 14 older houses that repeatedly flooded were purchased, dismantled, and removed using funding from the Federal Emergency Management Agency (F.E.M.A). A riparian buffer was planted and some wetland restorations were incorporated into stormwater management installations along the local highways. When the waters of the Swatara rise, the local municipality closes the roads into the floodplain. Nobody lives or works there anymore, so no one has any reason to enter. There’s no need to rescue stubborn residents who refused advice to evacuate. Sightseers can park and stand on the hill behind the barricades and take all the photographs they like.A new Pennsylvania Turnpike bridge across Swatara Creek features wide passage for the stream below. Water flowing in the floodplain can pass under the bridge without being channelized toward the path where the stream normally flows in the center. The black asterisk-shaped floats spin on the poles to help deflect debris away from the bridge piers. (flood crest on July 26, 2018)People are curious when a waterway floods and they want to see it for themselves. Wouldn’t it be wise to anticipate this demand for access by being ready to accommodate these citizens safely? Isn’t a parking lot, picnic area, or manicured park safer and more usable when overlooking the floodplain as opposed to being located in it? Wouldn’t it be a more prudent long-term investment, both financially and ecologically, to develop these improvements on higher ground outside of flood zones?Now would be a good time to stop the new construction and the rebuilding in floodplains. Aren’t the risks posed to human life, water quality, essential infrastructure, private property, and ecosystems too great to continue?Isn’t it time to put up the white flag and surrender the floodplains to the floods? That’s why they’re there. Floodplains are for flooding.
There are two Conewago Creek systems in the Lower Susquehanna River Watershed. One drains the Gettysburg Basin west of the river, mostly in Adams and York Counties, then flows into the Susquehanna at the base of Conewago Falls. The other drains the Gettysburg Basin east of the river, flowing through Triassic redbeds of the Gettysburg Formation and York Haven Diabase before entering Conewago Falls near the south tip of Three Mile Island. Both Conewago Creeks flow through suburbia, farm, and forest. Both have their capacity to support aquatic life impaired and diminished by nutrient and sediment pollution.
This week, some of the many partners engaged in a long-term collaboration to restore the east shore’s Conewago Creek met to have a look at one of the prime indicators of overall stream habitat health—the fishes. Kristen Kyler of the Lower Susquehanna Initiative organized the effort. Portable backpack-mounted electrofishing units and nets were used by crews to capture, identify, and count the native and non-native fishes at sampling locations which have remained constant since prior to the numerous stream improvement projects which began more than ten years ago. Some of the present-day sample sites were first used following Hurricane Agnes in 1972 by Stambaugh and Denoncourt and pre-date any implementation of sediment and nutrient mitigation practices like cover crops, no-till farming, field terracing, stormwater control, nutrient management, wetland restoration, streambank fencing, renewed forested stream buffers, or modernized wastewater treatment plants. By comparing more recent surveys with this baseline data, it may be possible to discern trends in fish populations resulting not only from conservation practices, but from many other variables which may impact the Conewago Creek Warmwater Stream ecosystem in Dauphin, Lancaster, and Lebanon Counties.
So here they are. Enjoy these shocking fish photos.
Matt Kofroth, Watershed Specialist with the Lancaster County Conservation District, operates the electrofishing wand in Conewago Creek while his team members prepare to net and collect momentarily-stunned fish. Three other electrofishing units operated by staff from the Susquehanna River Basin Commission and aided by teams of netters were in action at other sample locations along the Conewago on this day.Really big fish, such as this Common Carp (Cyprinus carpio), were identified, counted, and immediately returned to the water downstream of the advancing electrofishing team. Koi of the garden pond are a familiar variety of Common Carp, a native of Asia.Other fish, such as the Swallowtail Shiner, Redbreast Sunfish (Lepomis auritus), Fallfish, and suckers seen here, were placed in a sorting tank.Fallfish (Semotilus corporalis) are very active and require plenty of dissolved oxygen in the water to survive. Fallfish, Rainbow Trout (Oncorhynchus mykiss), and Smallmouth Bass (Micropterus dolomieu) were quickly identified and removed from the sorting tank for release back into the stream. Other larger, but less active fish, including suckers, quickly followed.Small fish like minnows were removed from the sorting tank for a closer look in a hand-held viewing tank. This Fathead Minnow (Pimephales promelas) was identified, added to the tally sheet, and released back into the Conewago. The Fathead Minnow is not native to the Susquehanna drainage. It is the minnow most frequently sold as bait by vendors.A breeding condition male Bluntnose Minnow (Pimephales notatus).The Cutlips Minnow (Exoglossum maxillingua) is a resident of clear rocky streams. Of the more than 30 species collected during the day, two native species which are classified as intolerant of persisting stream impairment were found: Cutlips Minnow and Swallowtail Shiner.This young River Chub (Nocomis micropogon) is losing its side stripe. It will be at least twice as large at adulthood.The Eastern Blacknose Dace (Rhinichthys atratulus) is found in clear water over pebble and stone substrate..The Longnose Dace (Rhinichthys cataractae) is another species of pebbly rocky streams.A juvenile Golden Shiner (Notemigonus crysoleucas). Adults lack the side stripe and grow to the size of a sunfish.A Swallowtail Shiner (Notropis procne) and a very young White Sucker (Catostomus commersonii) in the upper left of the tank.A Spotfin Shiner (Cyprinella spiloptera).A breeding male Spotfin Shiner. Show-off!The Margined Madtom (Noturus insignis) is a small native catfish of pebbly streams.The Banded Killifish (Fundulus diaphanus) is adept at feeding upon insects, including mosquitos.A young Rock Bass (Ambloplites rupestris). This species was introduced to the Susquehanna and its tributaries.The Greenside Darter (Etheostoma blennioides) is not native to the Susquehanna basin. The species colonized the Conewago Creek (east) from introduced local populations within the last five years.The Tessellated Darter (Etheostoma olmstedi) is a native inhabitant of the Susquehanna and its tributaries.The stars of the day were the American Eels (Anguilla rostrata).After collection, each eel was measured and weighed using a scale and dry bucket. This specimen checked in at 20 inches and one pound before being released.Prior to the construction of large dams, American Eels were plentiful in the Susquehanna and its tributaries, including the Conewago. They’ve since been rarities for more than half a century. Now they’re getting a lift.American Eels serve as an intermediate host for the microscopic parasitic glochidia (larvae) of the Eastern Elliptio (Elliptio complanata), a declining native freshwater mussel of the Lower Susquehanna River Watershed. While feeding on their host (usually in its gills), the glochidia cause little injury and soon drop off to continue growth, often having assured distribution of their species by accepting the free ride. Freshwater mussels are filter feeders and improve water quality. They grow slowly and can live for decades.American Eels are a catadromous species, starting life as tiny glass eels in the saltwater of the Atlantic Ocean, then migrating to tidal brackish marshes and streams (males) or freshwater streams (females) to mature. This 20-incher probably attempted to ascend the Susquehanna as an elver in 2016 or 2017. After hitching a ride with some friendly folks, she bypassed the three largest dams on the lower Susquehanna (Conowingo, Holtwood, and Safe Harbor) and arrived in the Conewago where she may remain and grow for ten years or more. To spawn, a perilous and terminally fatal journey to the Sargasso Sea awaits her. (You may better know the area of the Sargasso Sea as The Bermuda Triangle…a perilous place to travel indeed!)
SOURCES
Normandeau Associates, Inc. and Gomez and Sullivan. 2018. Muddy Run Pumped Storage Project Conowingo Eel Collection Facility FERC Project 2355. Prepared for Exelon.
Stambaugh, Jr., John W., and Robert P. Denoncourt. 1974. A Preliminary Report on the Conewago Creek Faunal Survey, Lancaster County, Pennsylvania. Proceedings of the Pennsylvania Academy of Sciences. 48: 55-60.
It has not been a good summer if you happen to be a submerged plant species in the lower Susquehanna River. Regularly occurring showers and thunderstorms have produced torrents of rain and higher than usual river stages. The high water alone wouldn’t prevent you from growing, colonizing a wider area, and floating several small flowers on the surface, however, the turbidity, the suspended sediment, would. The muddy current casts a dirty shadow on the benthic zone preventing bottom-rooted plants from getting much headway. There will be smaller floating mats of the uppermost leaves of these species. Fish and invertebrates which rely upon this habitat for food and shelter will find sparse accommodation…better luck next year.
Due to the dirty water, fish-eating birds are having a challenging season as they try to catch sufficient quantities of prey to feed themselves and their offspring. A family of Ospreys (Pandion haliaetus) at Conewago Falls, including recently fledged young, were observed throughout this morning and had no successful catches. Of the hundred or more individual piscivores of various species present, none were seen retrieving fish from the river. The visibility in the water column needs to improve before fishing is a viable enterprise again.
Ospreys competing for a suitable fishing perch. Improving water conditions in the coming week should increase their success as predators.Versatile at finding food, adult Bald Eagles are experienced and know to be on the lookout for Ospreys with fish, a meal they can steal through intimidation.
While the submerged plant communities may be stunted by 2017’s extraordinary water levels, there is a very unique habitat in Conewago Falls which endures summer flooding and, in addition, requires the scouring effects of river ice to maintain its mosaic of unique plants. It is known as a Riverine Grassland or scour grassland.
The predominant plants of the Riverine Grasslands are perennial warm-season grasses. The deep root systems of these hardy species have evolved to survive events which prevent the grassland from reverting to woodland through succession. Fire, intense grazing by wild herd animals, poor soils, drought, and other hardships, including flooding and ice scour, will eliminate intolerant plant species and prevent an area from reforesting. In winter and early spring, scraping and grinding by flood-driven chunk ice mechanically removes large woody and poorly rooted herbaceous growth from susceptible portions of the falls. These adverse conditions clear the way for populations of species more often associated with North America’s tall grass prairies to take root. Let’s have a look at some of the common species found in the “Conewago Falls Pothole Rocks Prairie”.
Big Bluestem (Andropogon gerardi), seen heregrowing in the cracks of a pothole rock. High water nourishes the plant by filling the crevices with nutrient-loaded sediment. This species evolved with roots over three feet deep to survive fires, trampling by bison, and drought.Freshwater Cordgrass (Spartina pectinata) does well with its roots in water. It creates exceptional bird habitat and grows in the falls and on ice-scoured small islands in free-flowing segments of the Susquehanna River downstream.Switchgrass (Panicum virgatum), like Big Bluestem, is one of the tall grass prairie species and, like Freshwater Cordgrass, grows in near pure stands on ice-scoured islands. It takes flooding well and its extensive root system prevents erosion.Though not a grass, Water Willow (Justicia americana) is familiar as a flood-enduring emergent plant of river islands, gravel bars, and shorelines where its creeping rhizome root system spreads the plant into large masses. These stands are often known locally as “grass beds”. This member of the acanthus family provides habitat for fish and invertebrates among its flooded leaves and stems. Its presence is critical to aquatic life in a year such as this.
The Conewago Falls Riverine Grassland is home to numerous other very interesting plants. We’ll look at more of them next time.
SOURCES
Brown, Lauren. 1979. Grasses, An Identification Guide. Houghton Mifflin Company. New York, NY.
