The U.S. Geological Survey says “excess fertilizer and manure applied to the Chesapeake Bay’s Eastern Shore are causing poor-quality water flows in streams that flow into the bay.” In a report, USGS says the Eastern Shore, part of the DelMarVa peninsula, receives nearly twice as much nitrogen and phosphorus per square mile as other parts of the watershed feeding the Bay, due primarily to crop and livestock production. “More than 90 percent of nitrogen and phosphorus reaching the land in the Eastern Shore is applied as inorganic fertilizers, manure or comes from crops which use nitrogen from the atmosphere,” says USGS.
The excess nutrients, when washed into the Bay, encourage growth of algae and plants that deplete oxygen needed for fish and shellfish. The EPA and states in the Chesapeake watershed are trying to limit nutrient runoff and improve water quality. A USGS hydrologist said nitrogen and phosphorus levels in surface waters in the Bay are among the highest in the nation.