On a blustery day in May, I visited Conowingo Dam. I had been there many times before, but I wanted to get a fresh look to see if I could get some insight into the controversy surrounding this mammoth dam across the Susquehanna River, northeast of Baltimore.
The day turned out to be as significant as it was blustery. Thirty-five-knot gusts pounded whitecaps against the torrents splashing down the face of the dam. The wind had come spinning from the first hurricane of the season, which was, then, churning off the Carolina Capes. At the same time, a political storm was building on the horizon as State of Maryland announced a lawsuit to force the Environmental Protection Agency to, in turn, force Pennsylvania and New York to live up to their pledges to clean up the Chesapeake Bay.
These three separate concepts, Conowingo Dam, hurricanes, and environmental restoration in New York and Pennsylvania, while seeming disparate, are intrinsically woven together.
On my way to visit the dam, I was lured off the road by signs leading to Susquehanna State Park. I drove down the winding slope through the woods and emerged by an old stone water mill. I parked and sat on a bench overlooking the river. It was as immense as I remembered, almost Mississippian in its scale. And then I looked at the map. It showed an island in the middle of the river. The river here is actually three times wider than what I could see, and what I could see was still impressive. According to the map, it’s more than three quarters of a mile wide at that point.
On his “voyages of discoverie” in 1608 and 1609, Captain John Smith kedged his little pinnace up the river as far as the first falls, just south of this point, where the town of Port Deposit sits now. The Delaware Indians called the river Sisa’we’hak’hanna, which means “Oyster River.” It’s 444 miles long, the longest river this side of the Mississippi. Its main branch flows out of Otsego Lake all the way up in Cooperstown, New York.
The river’s drainage basin, or watershed, covers 27,500 square miles, including nearly half of all the land in Pennsylvania. That’s a little more than one third watershed of the entire Chesapeake Bay. The Susquehanna supplies no less than half of the Chesapeake’s fresh water, as much as the Potomac and all the other 100,000 rivers and creeks combined.
That’s about 25 billion gallons of water flowing into the Bay at its mouth at Havre de Grace every day. Imagine the City of Annapolis, all eight square miles of it, as flat as a pool table. If you were standing on one of the squares, that amount of water would come up to your knees.
Now imagine a funnel about 200 miles across at the top and less than one mile at the spout. That 25 billion gallons of water comprises all the rainfall that lands in that watershed, and then it funnels down through the spout. That’s 25 billion gallons every day. And much more during heavy storms. Much, much more during a hurricane.
Now imagine a dam across that spout.
The dam spans the river about ten miles above where it enters into the Chesapeake Bay at Havre de Grace, which is about 45 miles northeast of Baltimore. When I arrived at the dam, I took the walkway down to the river’s edge. The 100-foot-tall concrete expanse of the dam stretches nearly a mile across. The massive maze of towers with its web of high-tension wires sprouts out of the hydroelectric generation station that dominates the nearer section of the wall. Water churned down the spillways in the middle. The flow of the water coming over the dam formed one-foot waves in the river below, beaten up into whitecaps by the wind sweeping up against the current.
There were half a dozen photographers lined up along the river’s edge, each one following American Bald Eagles through a telephoto lens that looked like field artillery mounted on a tripod. There were as many eagles to be seen, some swooping in the wind gusts, others sitting it out, perched on driftwood logs lodged on a rocky island in the middle of the river. “There aren’t as many eagles this time of year,” one of the birders muttered. “I guess there aren’t that many fish to catch.”
While the eagles weren’t getting much in the way of fish, the human fishermen seemed undaunted. There were dozens there with spin-casting rods working the outflow at the base of the dam. Some were dropping lines from the concrete walkway, but there were two men in waders, casting while standing in water up to their waists. The guys in the water were getting all the action—hooking and releasing good-sized shad and small rockfish. I was envious of their fun; I was hoping to do some angling myself, but I had brought my fly rod, which would have been useless in this wind.
The dam is operated by Exelon Power Corporation, which also owns Baltimore Gas & Electric. Several years ago, as a member of the Chesapeake Bay Program’s Citizen Advisory Committee, I took a tour of the hydroelectric generation station built into the structure of the dam. The tour group made its way past the array of the 11 massive turbines, some driving generators rated for 36 megawatts, enough electricity to power 15,000 homes, and four newer ones generating 65 megawatts. The dam transmits about 1.6 billion kilowatt-hours every year, mainly to the Philadelphia area.
Wandering through the cavernous interior of the dam, I couldn’t help imagining that scene from Dr. Frankenstein’s laboratory, just as the mad scientist was about to pull the switch to animate the monster. Seven of the turbines date back to the dam’s beginning in 1928, and they look their age.
The project started in 1926. When it was completed after two years of work by as many as 5,000 workers, dozens of whom were killed in construction accidents, Conowingo was the second largest hydroelectric dam in the country, topped only by the works at Niagara Falls.
The reservoir behind the dam is called Conowingo Lake and it covers 9,000-acres, ten times larger than Central Park. Its 14-mile length stretches north across the Pennsylvania border. The reservoir supplies drinking water to Baltimore as well as a suburb of Philadelphia. It also supplies cooling water for the Peach Bottom Nuclear Generation Station on the west bank of the lake.
Damming the river here flooded the site of the original town of Conowingo, which was moved to its present location about a mile up the hill. The highway, US Route 1, which once crossed a bridge in the old town, now runs across the rim of the dam.
The dam has 53 flood control gates. They were all opened at once for the first time in 1936, when an unnamed hurricane swept up the coast. They were opened again in 1972 to let the flood waters of Hurricane Agnes flow through, but the water level still rose to within five feet of the top of the dam. Engineers were so afraid that the dam would burst from the strain, that they planted explosives to blow a section of the wall to relieve the pressure. Fortunately for the residents downstream, that precaution proved unnecessary. The water rose to a record 36.85 feet.
In 2011, 44 flood gates were opened because Tropical Storm Lee had dumped enough water into the funnel to raise the height to 32.41 feet. The residents of Port Deposit, five miles downstream, evacuated their homes until the river subsided.
The most recent event occurred in July of 2018, when storm water carried debris through 20 of the 53 floodgates. This was not from a named storm. The weather was part of a trend linked to climate change. As the atmosphere heats up, storm events become more frequent and each event becomes more severe.
The 2018 storm brought day after day of heavy rain, raising the river level to 26.25 feet. Debris flowing over the dam included everything from entire tree trunks to portable toilets, causing navigational nightmares for commercial vessels and pleasure boats alike, and littering the shorelines with many tons of trash.
At the time, I served as the Riverkeeper for the West and Rhode Rivers, and I worked with a group of high-school students to clean up the debris from the end of the Mayo peninsula in southern Anne Arundel County. These volunteers call themselves the Clean Creeks Football Club. Made up mainly of soccer players from Southern and South River High Schools, young men and women alike, they spend their summer weekends in canoes and kayaks, cleaning up the shores of nearby rivers and creeks. On this one day, we filled a 40-yard dumpster with driftwood and junk that had washed up on just 100 yards of the shore of Beverly Beach. Anne Arundel County has 523 miles of shoreline.
But the driftwood and the trash are just the visible manifestation of the pollutants carried over the dam by storm water. Less visible, but more damaging, are the sediment and nutrients, untreated sewage, heavy metals, and other nastiness.
Sediment is the dirt that’s dissolved into the water when stream banks and shorelines erode. Too much sediment makes the water cloudy, blocking sunlight from reaching grasses growing on the bottom of the Bay, and smothers oysters and clams. Imagine how much dirt there is in all the farmland in central Pennsylvania, in that funnel of the watershed.
And on those farms there are cows. And pigs. And lots of other animals, all doing what comes naturally. That effluent contains nitrogen and phosphorus, as does all the fertilizer spread on those thousands of acres of fields throughout central Pennsylvania and up into New York. Towns and cities in the watershed contribute their share of nutrient pollution by way of poorly treated sewage.
Nitrogen and phosphorus are great for helping vegetation grow, which is a good thing. But when storm water washes it into the waterways, it helps the algae grow, which is a bad thing. Too much of these nutrients promote too much algae. When the algae blooms, it clouds the water, and when it dies, it settles to the bottom and sucks up all the oxygen, creating dead zones. Fish can swim away from dead zones. Oysters and clams can’t move out of the way. They suffocate.
Conowingo Lake did a good job capturing sediment and nutrients flowing down the river for nearly 100 years, trapping an average of 3.5 million pounds of phosphorus and four billion pounds of sediment every year since the dam opened in 1928, according to information published by the Chesapeake Bay Program. That’s about a third of the phosphorus and half of the sediment that flows down the river into the Bay every year.
But then it filled up.
In 2015, a U.S. Geological Survey report found that the reservoir had reach 92 percent of its capacity.
So while the dam used to be considered a trap for all the pollution coming down the river, further study has concluded that the reservoir behind the dam has filled up over time. Any considerable storm—a hurricane, for example—sends tons of sediment, nutrients, pollutants, and debris over the top of the dam and into the Bay. The reservoir is so large, dredging it is not an option. The states upstream need to clean up their act to lessen the amount of pollution they send down the river, according to Maryland’s Attorney General Brian Frosh.
Frosh sent a letter of intent on behalf of Maryland, Virginia, and the District of Columbia to the Environmental Protection Agency on that same day in May that I visited the dam. He demanded that the EPA enforce the requirement for pollution management plans or face a federal lawsuit.
That same day, Will Baker, President of the Chesapeake Bay Foundation, sent another letter of intent to sue to the federal agency on behalf of Anne Arundel County, the Maryland Watermen’s Association, and Virginia cattle farmers Jeanne Hoffman and Bobby Whitescarver.
“EPA has failed to uphold its Clean Water Act responsibilities,” Baker said in a statement. “It has failed to implement the Chesapeake Clean Water Blueprint...It is essential the courts hold EPA accountable,” Baker wrote. “There is no doubt that if Pennsylvania and New York fail to do their fair share, the Bay will never be saved.”
When I left the fishermen at the base of the dam, I thought I had a pretty clear idea of the issues, but then I took a drive across the top of the dam and stopped along the highway on the hilltop overlooking the reservoir. From there, I could see tons of trees and trash piled up in the corners of the lake. It hit me then, that the problems on the downstream side won’t be solved until the problems upstream are resolved.
In the next article in this three-part series, Conowingo Dam Part II: Upstream Neglect & Accountability, we’ll take a deeper look at who’s responsible for this mess and what can be done about it.
