Maryland's Harford and Cecil counties are balking at being forced to go on a multibillion-dollar mandatory "pollution diet" to clean up the Chesapeake Bay. The reason is that, even as they are being forced to spend billions mitigating relatively tiny amounts of runoff, no one is addressing the main source of Bay pollution, which can at any moment make all their efforts for naught.

The Conowingo Dam, which straddles the border between the two counties, is owned by Exelon. It generates about 1.6 billion kilowatt hours of electricity annually and provides a key backup power source when the regional electrical grid goes down. But a study by the U.S. Geological Survey found that major storms are responsible for up to 40 percent of the sediment flowing into the Bay, because the Conowingo Reservoir behind the dam traps sediment and pollutants carried downstream by the Susquehanna River, the Bay's largest tributary. For the counties' attempts to refocus attention on the main problem, the Chesapeake Bay Foundation calls them "obstructionist."

Last year, 44 of the dam's 53 flood gates had to be opened during Tropical Storm Lee, sending 19 million tons of sediment into the Bay. On Oct. 30 of this year, five flood gates were opened in the wake of Hurricane Sandy, sending millions more gallons of polluted water downstream.

"The state's been focused on the farmers, been focused on the counties, been focused on property owners and making them spend significant amounts of dollars to clean up a small amount of sediment, and yet you can see here today, we have a significant problem upstream," Maryland state Sen. E.J. Pipkin, R, said at a Nov. 1 press conference.

Beth McGee, a senior scientist at the foundation, called county officials' complaints about the dam "a red herring" -- a strange way for the self-described watchdog of the Bay to describe its largest single source of pollution. Instead of leading the charge and addressing the pollution problems created by the dam, the foundation would rather attack those who do. The foundation is currently intervening in a federal lawsuit by several business groups against the EPA's "pollution diet."

But it's perfectly rational for Harford and Cecil counties' officials to complain about being forced to "tax rain," as Pipkin put it, and spend millions of dollars on pollution mitigation efforts to prevent a relatively small amount of runoff from entering the Bay, when all their efforts could be erased by one major storm.