The Chesapeake Bay's health remained steady overall last year, despite heavy rains that normally flush pollution into its waters, University of Maryland scientists reported Friday. Declines in Eastern Shore rivers, however, indicated problems with polluted farm runoff there, researchers said.
The bay as a whole earned a 45 percent score, a 'C' grade for the second straight year in the annual ecological health checkup performed by the university's Center for Environmental Science. Some rivers feeding into the Chesapeake showed improvements, while others worsened.
Water quality made gains last year in the James River in Virginia, which researchers credited to the greater percentage of its watershed than other rivers covered with forests, which can soak up rainfall and reduce polluted runoff.
Upgrades to sewage treatment plants also appear to be helping some rivers, researchers suggested. The Patapsco and Back rivers near Baltimore remain the bay's least healthy, combining for an F on the university's report card, but even they showed some improvements.
Rivers that drain mainly agricultural land lost ground last year, according to the researchers. The Choptank River got a C-minus and upper Shore rivers such as the Elk, Sassafras, Chester and Miles rated Ds, down from the previous year. Scientists blamed the low scores on a rainfall of more than 50 inches on the Delmarva Peninsula that washed fertilizer and animal waste from fields.
"To be blunt, it's the fertilizer and chicken manure that's causing the problems there,'' said William Dennison, a vice president with the environmental science center. "All those Eastern Shore tributaries are showing we're not going in the right direction."
The bay's water remains too murky, Dennison said, and became less clear last year. But when researchers accounted for the heavy rain washing more sediment into the water, he said, clarity actually showed slight improvement.
Maryland scientists also found key fish populations, including blue crabs and striped bass, improved last year. Despite reports earlier this month that the bay's crabs are in a serious slump and striped bass are declining, Dennison said he believed that "we've got a handle" on sustaining their numbers.