How Did This Happen: A Conowingo Dam Update

The purpose of the Conowingo Dam was to trap nitrogen, phosphorus and sediment pollution to keep it from reaching the main stem of the Chesapeake Bay. Which it did — until it overflowed.

The impact of this overflow goes beyond closed beaches and boating hazards.

All Maryland rivers — including the Magothy and Patapsco — were affected by the record amounts of rain in July throughout the watershed, said Bruce Michael, the resource assessment service director at the Maryland Department of Natural Resources.

With the continued heavy rainfall, this problem isn’t going away quickly.

“We’re just at the beginning of hurricane season here, so the thought that this is an unprecedented event or that this may just resolve itself is really unlikely,” said Betsy Nicholas, executive director of Waterkeepers Chesapeake.

In response to the rain, additional floodgates have been opened to relieve pressure from the water. During one weekend, “flows were over 100,000 cubic feet per second,” Michael said.

“This is a prolonged event. Grounds are already saturated, so any time we have these continuous thunderstorms and heavy rains and downpours, the ground and reservoirs can’t absorb that water,” Michael said. “It basically runs off and goes directly into the streams and rivers.”

The Chesapeake Bay watershed states (Maryland, Pennsylvania, New York, Delaware, Virginia and West Virginia, as well as the District of Columbia) have agreed to share some of the responsibility for the area behind the dam being silted in.

Officials from Exelon Corporation, the owner of the Conowingo Dam, have been unwilling to take responsibility for the sediment build-up, Nicholas said.

“While Exelon didn’t produce that sediment, their dam has forever changed the flow of that river, and the river does not flow in a natural manner. That sediment would not be there and would not have accumulated there if it weren’t for Exelon’s Conowingo Dam,” Nicholas said. “They need to play a part in the responsible management of that sediment and that risk to downstream waterways.”

However, the Maryland Department of the Environment ordered Exelon Corporation to be accountable for a major portion of the pollution reduction, or contribute significant funding.

The Chesapeake Bay Foundation filed a motion to support the state’s lawsuit, according to a press release.

“We have a unique interest in the outcome of this case. Chesapeake Bay Foundation has worked for decades to reduce pollution coming down the Susquehanna River and despoiling the Chesapeake Bay,” said CBF Vice President for Litigation Jon Mueller, according to the press release. “Most recently, we commissioned an economic study proving that Exelon can make a sizeable contribution toward rectifying harm to natural resources and the bay exacerbated by the dam. As the recent heavy rains and resulting discharges from the dam demonstrated, it is critical that CBF be permitted to present our information and represent the interests of our members to the court.”

Waterkeepers Chesapeake also filed to defend the Section 410 water quality certification, which declares that a project will not impact Maryland water quality standards.

“The 401 certification included measures to address upstream pollution, specifically nutrient pollution: nitrogen and phosphorus that are coming through the dam,” Nicholas said. “We are seeing what the state of Maryland was trying to address in action right now.”

Exelon filed three court challenges in response to its 401 certification, which was published May 11: one administrative challenge at the state agency level, one in Maryland state court and one in federal court. Since 2009, the company has been going through the process to renew its license on the dam for 50 more years.

“It’s a pretty big concern that Exelon is filing all these legal challenges to try and keep the state from putting those protections in place when, right at this exit time, we’re seeing why those measures and those protections are so critically important,” Nicholas said.

If you want to help, there are a few options. First, be conservative with fertilizers and other lawn treatments. If you’re changing the oil in your car, make sure to properly dispose of the oil. If you think your car has a leak, take care of it right away.

To help control the runoff, you can plant trees, or put a rain barrel or rain garden on your property.

“Whatever winds up on the road in these rain events winds up in our streams and rivers,” Michael said.