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)
Three Mile Island flooding from Agnes 1972.
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.
Three Mile Island flooding from Agnes 1972.
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.
Three Mile Island flooding from Agnes 1972.
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.
Three Mile Island flooding from Agnes 1972.
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.

Pick Up and Get Out of the Floodplain

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.

Get Out of the Floodplain…And Get Your Stuff Out Too!

After threading its way through waves of Saharan dust plumes, Tropical Storm Isaias, or the remnants thereof, is making a run up the eastern seaboard toward the lower Susquehanna watershed.

Isaias formed just off the northernmost tip of the South American continent.  It drifted north in a narrow pocket between two waves of the Saharan dust plume and, on July 30, strengthened to tropical storm status while in the vicinity of Puerto Rico.  (CIRA/NOAA image)
In this image taken on Friday, note the position of the fast-moving dust plume that was to the southeast of Isaias just a day earlier.  With the storm now clear of the dry Saharan air, it strengthens to become Hurricane Isaias.  (CIRA/NOAA image)
On Friday, the National Hurricane Center issues advisors expecting the strengthening Isaias to sweep the Atlantic coasts of Florida, Georgia, and South Carolina as a hurricane with winds of 74 miles per hour or greater.  (NOAA/National Hurricane Center image)
Then on Saturday, Isaias appears to be back in the dirt.  Did the counterclockwise rotation of the atmosphere around Isaias draw in Saharan dust and dry air to weaken the storm?  Whatever the cause, Isaias is downgraded to a strong tropical storm with maximum sustained winds of 70 miles per hour.  (CIRA/NOAA image)
The latest image of Tropical Storm Isaias.  (CIRA/NOAA image)
The latest forecast projects Isaias will briefly reach hurricane status later today before making landfall in South Carolina and again weakening.  (NOAA/National Hurricane Center image)
Tropical Storm Isaias is expected to bring heavy rain to the lower Susquehanna valley and the Cheapeake Bay region tomorrow (Tuesday).  (NOAA/National Hurricane Center image)

Heavy rain and flooding appears likely, particularly east of the Susquehanna.  Now might be a good time to clean up the trash and garbage that could clog nearby storm drains or otherwise find its way into your local waterway.  NOW is the time to get all your stuff out of the floodplain!  The car, the camper, the picnic table, the lawn furniture, the kid’s toys, the soda bottles, the gas cans, the lawn chemicals, the Styrofoam, and all that other junk you’ve piled up.  Get that stuff cleaned up and out of the floodway.  And of course, get you and your pets out of the there too!

The Colorful Birds Are Here

You need to get outside and go for a walk.  You’ll be sorry if you don’t.  It’s prime time to see wildlife in all its glory.  The songs and colors of spring are upon us!

Flooding that resulted from mid-week rains is subsiding.  The muddy torrents of Conewago Falls are seen here racing by the powerhouse at the York Haven Dam.
Receding waters will soon leave the parking area at Falmouth and other access points along the river high and dry.
Migrating Yellow-rumped Warblers are currently very common in the riparian woodlands near Conewago Falls.  They and all the Neotropical warblers, thrushes, vireos, flycatchers are moving through the Susquehanna watershed right now.
A Baltimore Oriole feeds in a riverside maple tree.
Ruby-crowned Kinglets are migrating through the Susquehanna valley.  These tiny birds may be encountered among the foliage of trees and shrubs as they feed upon insects .
Gray Catbirds are arriving.  Many will stay to nest in shrubby thickets and in suburban gardens.
American Robins and other birds take advantage of rising flood waters to feed upon earthworms and other invertebrates that are forced to the soil’s surface along the inundated river shoreline.
Spotted Sandpipers are a familiar sight as they feed along water’s edge.
The Yellow Warbler (Setophaga petechia) is a Neotropical migrant that nests locally in wet shrubby thickets.  Let your streamside vegetation grow and in a few years you just might have these “wild canaries” singing their chorus of “sweet-sweet-sweet-I’m-so-sweet” on your property.

If you’re not up to a walk and you just want to go for a slow drive, why not take a trip to Middle Creek Wildlife Management Area and visit the managed grasslands on the north side of the refuge.  To those of us over fifty, it’s a reminder of how Susquehanna valley farmlands were before the advent of high-intensity agriculture.  Take a look at the birds found there right now.

Red-winged Blackbirds commonly nest in cattail marshes, but are very fond of untreated hayfields, lightly-grazed pastures, and fallow ground too.  These habitats are becoming increasingly rare in the lower Susquehanna region.  Farmers have little choice, they either engage in intensive agriculture or go broke.
Nest boxes are provided for Tree Swallows at the refuge.
Numbers of American Kestrels have tumbled with the loss of grassy agricultural habitats that provide large insects and small rodents for them to feed upon.
White-crowned Sparrows (Zonotrichia leucophrys) are a migrant and winter resident species that favors small clumps of shrubby cover in pastures and fallow land.
When was the last time you saw an Eastern Meadowlark (Sturnella magna) singing “spring-of-the-year” in a pasture near your home?
And yes, the grasslands at Middle Creek do support nesting Ring-necked Pheasants (Phasianus colcichus).  If you stop for a while and listen, you’ll hear the calls of “kowk-kuk” and a whir of wings.  Go check it out.

And remember, if you happen to own land and aren’t growing crops on it, put it to good use.  Mow less, live more.  Mow less, more lives.

2018 Migration Count Summary: Rainout

If you were a regular visitor to this website during the autumn of 2017, you will recall the proliferation of posts detailing the bird migration at Conewago Falls during the season.  The lookout site among the Pothole Rocks remained high and dry for most of the count’s duration. 

In the fall of 2018, those lookout rocks were never to be seen. There was to be no safe perch for a would-be observer. There was no attempt to conduct a tally of passing migrants. If you live in the lower Susquehanna River drainage basin, you know why—rain—record setting rain.

Annual precipitation during 2018 as indicated by radar.  Note the extensive areas in pink.  They received in excess of 70 inches of precipitation during 2018, much of it during the second half of the year.  (NOAA/National Weather Service image)
Average annual rainfall.  Most of the lower Susquehanna drainage basin receives an average of just over 40 inches of rain each year.  (NOAA/National Weather Service image)
Departure from normal annual precipitation totals.  Note the extensive areas of greater than 20 inches of precipitation above normal (pink).  Severe flooding occurred on many streams during numerous events throughout the second half of 2018.  Note the closer to normal totals in central New York in the upper Susquehanna watershed.  The lesser amounts of rain there and the localized pattern of the flooding events in Pennsylvania prevented the main stem of the lower Susquehanna from experiencing catastrophic high water in 2018.  (NOAA/National Weather Service image)   
Though there has been no severe flooding, frequent rain events in the Susquehanna watershed have maintained persistently high river levels in Conewago Falls.  Pothole Rocks seen here on December 9 during an ebb in the flow were soon inundated again as rains fell in the Susquehanna basin upstream. 
Of course, each time the river receded it left behind a fresh pile of plastic garbage.  What didn’t end up on the shoreline found its way to Chesapeake Bay…then on to the Atlantic.  Is that your cooler? 

Put Up the White Flag

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.

They Call Me the Wanderer

It’s been an atypical summer.  The lower Susquehanna River valley has been in a cycle of heavy rains for over a month and stream flooding has been a recurring event.  At Conewago Falls, the Pothole Rocks have been inundated for weeks.  The location used as a lookout for the Autumn Migration Count last fall is at the moment submerged in ten feet of roaring water.  Any attempt to tally the migrants which are passing thru in 2018 will thus be delayed indefinitely.  Of greater import, the flooding at Conewago Falls is impacting many of the animals and plants there at a critical time in their annual life cycle.  Having been displaced from its usual breeding sites on the river, one insect species in particular seems to be omnipresent in upland areas right now, and few people have ever heard of it.

So, you take a cruise in the motorcar to your favorite store and arrive at the sprawling parking lot.  Not wishing to have your doors dented or paint chipped because you settled for a space tightly packed among other shopper’s conveyances, you park out there in the “boondocks”.  You know the place, the lightly-used portion of the lot where sometimes brush grows from cracks in the asphalt and you must be on alert for impatient consumers who throttle-up to high speeds and dash diagonally across the carefully painted grids on the pavement to reach their favorite parking destination in the front row.  Coming to a stop, you take the car out of gear, set the brake, disengage the safety belt, and gather your shopping list.  You grasp the door handle and, not wanting to be flattened  by one of the aforementioned motorists, you have a look around before exiting.

It was then that you saw the thing, hovering above your shiny bright hood.  For a brief moment, it seemed to be peering right through the windshield at you with big reddish-brown eyes.  In just a second or two, it turned its whole bronze body ninety degrees to the left and darted away on its cellophane wings.  Maybe you didn’t really get a good look at it.  It was so fast.  But it certainly was odd.  Oh well, time to walk inside a grab a few provisions.  Away you go.

Upon completion of your shopping, you’re taking the long stroll back to your car and you notice more of these peculiar creatures.  Two are coupled together and are hovering above someone’s automobile hood, then they drop down, and the lower of the two taps its abdomen on the paint.  You ask yourself, “What are these bizarre things?”

Meet the Wandering Glider (Pantala flavescens), also known as the Globe Wanderer or Globe Skimmer, a wide-ranging dragonfly known to occur on every continent with the exception of Antarctica.

Wandering Gliders sometimes arrive in the lower Susquehanna River valley in large numbers after catching a ride on sustained winds from southerly directions and will often fly and migrate in storm systems.  Conditions for such movements have been optimal in our region since mid-July.  These dragonflies will often hover above motor vehicle hoods and, after mating, females will deposit eggs upon them, apparently mistaking their glossy surface for small pools of water.

Wandering Gliders travel the globe, and as such are accomplished fliers.  Adults spend most of the day on the wing, feeding upon a variety of flying insects.  Days ago, I watched several intercepting a swarm of flying ants.  As fast as ants left the ground they were grabbed and devoured by the gliders.  Wandering Gliders are adept at taking day-flying mosquitos, often zipping stealthily past a person’s head or shoulders to grab one of the little pests—the would-be skeeter victim usually unaware of the whole affair.

Due to their nomadic life history, Wandering Gliders are opportunists when breeding and will lay eggs in most any body of freshwater.  Their larvae do not overwinter prior to maturity; adults can be expected in a little more than one to two months.  Repetitive flooding in the Lower Susquehanna River Watershed this summer may be reducing the availability of the best local breeding sites for this species—riverine, stream, and floodplain pools of standing water with prey.  This may explain why thousands of Wandering Gliders are patrolling parking lots, farmlands, and urban areas this summer.  And it’s the likely reason for their use of puddles on asphalt pavement, on rubber roofs, and in fields as places to try to deposit eggs.  Unfortunately, they may be as likely to succeed there as they are on your motor vehicle hood.

At this time a year ago, the airspace above the Diabase Pothole Rocks at Conewago Falls was jammed with territorial male Wandering Gliders.  Each male hovered at various locations around his breeding territory consisting of pools and water-filled potholes.  Intruders would quickly be dispatched from the area, then the male would resume his patrols from a set of repetitively-used hovering positions about six feet above the rocks.  Mating and egg-laying continued into late September.  The larvae, also called nymphs or naiads, were readily observed in many pools and potholes in early October and the emergence of juveniles was noted in mid-October.  The absence of flooding, the mild autumn weather, and the moderation of water temperatures in the pools and potholes courtesy of the sun-drenched diabase boulders helped to extend the 2017 breeding season for Wandering Gliders in Conewago Falls.  They aren’t likely to experience the same favor this year, but their great ability to travel and adapt should overcome this momentary misfortune.

A male Wandering Glider aggressively patrols his territory in the Diabase Pothole Rocks Microhabitat at Conewago Falls.  August 20, 2017.

A mating pair of Wandering Gliders continue flying non-stop above one of thousands of suitable breeding pools among the Diabase Pothole Rocks at Conewago Falls.  September 23, 2017.

A female (bottom)Wandering Glider has deposited eggs in a pool while flying in tandem with a male (top).  They’ll do the same thing on your automobile hood!  Conewago Falls Diabase Pothole Rocks Microhabitat.  September 23, 2017.

Wandering Glider larvae are at the top of the food chain in flooded potholes.  As they grew, these dragonfly larvae decimated the mosquito larvae which were abundant there earlier in the summer.  October 7, 2017.

A juvenile male Wandering Glider emerges from the pool where it fed and grew as a larva.  It remained at water’s edge on the surface of a sun-warmed diabase rock for several hours to dry its wings.  It soon flew away to parts unknown, possibly traveling hundreds or thousands of miles.  Look carefully at the wings for the beige dash marks on the forward edge near the terminal end.  Females lack this marking.  Conewago Falls Diabase Pothole Rocks Microhabitat.  October 14, 2017.

A Wandering Glider exuviae, the shed exoskeleton of a creature gone, but not forgotten.  October 14, 2017.

 

Shocking Fish Photos!

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.

S’more

The tall seed-topped stems swaying in a summer breeze are a pleasant scene.  And the colorful autumn shades of blue, orange, purple, red, and, of course, green leaves on these clumping plants are nice.  But of the multitude of flowering plants, Big Bluestem, Freshwater Cordgrass, and Switchgrass aren’t much of a draw.  No self-respecting bloom addict is going out of their way to have a gander at any grass that hasn’t been subjugated and tamed by a hideous set of spinning steel blades.  Grass flowers…are you kidding?

Big Bluestem in flower in the Riverine Grasslands at Conewago Falls.

O.K., so you need something more.  Here’s more.

Meet the Partridge Pea (Chamaecrista fasciculata).  It’s an annual plant growing in the Riverine Grasslands at Conewago Falls as a companion to Big Bluestem.  It has a special niche growing in the sandy and, in summertime, dry soils left behind by earlier flooding and ice scour.  The divided leaves close upon contact and also at nightfall.  Bees and other pollinators are drawn to the abundance of butter-yellow blossoms.  Like the familiar pea of the vegetable garden, the flowers are followed by flat seed pods.

The Partridge Pea can tolerate dry sandy soils.

But wait, here’s more.

In addition to its abundance in Conewago Falls, the Halberd-leaved Rose Mallow (Hibiscus laevis) is the ubiquitous water’s edge plant along the free-flowing Susquehanna River for miles downstream.  It grows in large clumps, often defining the border between the emergent zone and shore-rooted plants.  It is particularly successful in accumulations of alluvium interspersed with heavier pebbles and stone into which the roots will anchor to endure flooding and scour.  Such substrate buildup around the falls, along mid-river islands, and along the shores of the low-lying Riparian Woodlands immediately below the falls are often quite hospitable to the species.

Halberd-leaved Rose Mallow is a durable inhabitant of the falls.  Regular flooding keeps competing species at bay.  A taproot helps to safeguard against dislocation, allowing plants to grow in places subjected to turbulent currents.

Halberd-leaved Rose Mallow in bloom.  The similarity to cultivated members of the Hibiscus genus can readily be seen.  It is one of the showiest of perennial wildflowers in the floodplain.  Note the lobed, halberd-shaped leaves, source of its former species name militaris.

The seeds of Halberd-leaved Rose Mallow are contained in bladders which can float to assist in their distribution.  Some of these bladders cling to the dead leafless stems in winter, making it an easy plant to identify in nearly any season.

A second native wildflower species in the genus Hibiscus is found in the Conewago Falls floodplain, this one in wetlands.  The Swamp Rose Mallow (H. moscheutos) is similar to Halberd-leaved Rose Mallow, but sports more variable and colorful blooms.  The leaves are toothed without the deep halberd-style lobes and, like the stems, are downy.  As the common name implies, it requires swampy habitat with ample water and sunlight.

Swamp Rose Mallow in a sunny wetland.  This variety with solid-colored flowers (without dark centers) and pale green leaves and stems was formerly known as a separate species of  Swamp Rose Mallow, H. palustris.  Note that the flowers are terminal on the stems.

A few scattered specimens of a more typical variety of Swamp Rose Mallow are found on the shoreline and in the Riverine Grasslands of Conewago Falls.  The blooms are bright pink with darker centers and the leaf stems are robust and reddish.  This one is seen growing among Halberd-leaved Rose Mallow, with which it shares the characteristic of having flower stems growing from some of the upper leaf axils.  A variety with red-centered white flowers is often found throughout the plant’s range.

In summary, we find Partridge Pea in the Riverine Grasslands growing in sandy deposits left by flood and ice scour.  We find Halberd-leaved Rose Mallow rooted at the border between shore and the emergent zone.  We find Swamp Rose Mallow as an emergent in the wetlands of the floodplain.  And finally, we find marshmallows in only one location in the area of Conewago Falls.  Bon ap’.

Here’s S’more

SOURCES

Newcomb, Lawrence.  1977.  Newcomb’s Wildflower Guide.  Little, Brown and Company.  Boston, Massachusetts.

Summer Grasses

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 here growing 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.

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 recording-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 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.

The scene of dangerous tumbling rapids during high flows, 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.  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.

The initial segment, a crib dam constructed 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

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.