Md. can enforce dam cleanup

When the Conowingo Dam was built in 1928, it blocked a free-flowing section of the mighty Susquehanna River, creating a 14-mile-long, 9,000-acre reservoir at the head of the Chesapeake Bay near the Maryland-Pennsylvania line. While the dam has provided electricity for the region, the impacts on the river and the bay have been profound.

The hydropower dam has changed the flow of the river, blocked the migration of fish including shad, herring and eel, and its turbines kill millions of fish each year. Conowingo has also become a significant source of pollution.


For years, the dam's owner — Exelon Corporation — and its predecessors have avoided any responsibility for these impacts. Now Exelon is asking for a new federal license to operate the dam, and it is time for the company to bring the dam up to modern environmental standards. But let's not make Conowingo a scapegoat; let's make it an opportunity.

If you have heard of Conowingo, it might be because Maryland Gov.-elect Larry Hogan singled out the dam in his campaign as the leading cause of pollution in the bay.

A new assessment of the lower Susquehanna River from an interagency group led by the U.S. Army Corps of Engineers found that the reservoir behind Conowingo is essentially full of polluted sediment. Consider the dirt, contaminated with nitrogen and phosphorous from livestock waste and urban runoff, flowing off the land down the river, accumulating behind the dam for 90 years. Nearly 200 million tons of sediment, nutrients and other pollutants from the Susquehanna River have built up behind Conowingo Dam.

During large storms like hurricanes or nor'easters, floodwaters scoop up some of the pollution behind the dam and send it racing downstream into the bay. These acute doses of pollution foul the bay's waters and smother vital underwater grasses and other habitat.

The state of Maryland has a once-in-a-generation opportunity to reduce pollution from Conowingo and ensure that Exelon makes needed environmental improvements at the dam. We cannot miss this opportunity.

Exelon has applied to the Federal Energy Regulatory Commission for a new 46-year license to operate the dam. The Clean Water Act gives Maryland authority to require the dam's operations to meet state water quality standards before Exelon can receive a new license.

Federal regulators have largely ignored the dam's environmental problems. Now it falls to Maryland to make Exelon clean up its act. Scientists working for Maryland state agencies have already signaled that Exelon will not receive a license until it answers some tough questions about how Conowingo affects the Susquehanna River and the Chesapeake Bay.

If Governor-elect Hogan is sincere about restoring the Chesapeake Bay, he should make it a priority for his administration to determine the dam's full impacts on the health of the river and the bay, and require that Exelon take responsibility for its dam.

But that is only part of the answer. Conowingo Dam certainly contributes to the bay's problems, but fixing Conowingo is by no means a silver-bullet solution to cleaning up the bay. For that reason, Mr. Hogan must not abandon the ongoing multi-state comprehensive effort to restore the bay.

The high bacteria levels, seafood consumption advisories and other symptoms of pollution that we see in our local rivers and streams every day are the result of local pollution sources. The Susquehanna River carries 41 percent of the nitrogen, 25 percent of the phosphorus and 27 percent of the sediment entering the bay. The majority of the pollution comes from other local rivers and streams — mostly from Maryland.

The overall bay cleanup effort is a strategy to reduce pollution wherever it enters our waterways. Local programs such as wastewater treatment plant upgrades, programs to manage polluted runoff and best management practices for agriculture are being implemented all across the Chesapeake Bay watershed. Exelon needs to do its fair share, but so does everyone else.

The federal re-licensing gives Maryland a chance to act that won't come around again for another half century. Cleaning up Conowingo is only one piece of the puzzle to cleaning up the bay, but it's an important piece. The Susquehanna River and the Chesapeake Bay are regional and national treasures. We must fully address the dam's impacts on fisheries and clean water while we have the chance. And we must address all of the other sources of pollution, from Maryland and throughout the Chesapeake Bay watershed.

Concerned citizens can learn more and get involved at

Bob Irvin is President of American Rivers, a national non-profit river conservation organization, His email is