"Despite early progress reducing Chesapeake Bay pollution, levels of a key pollutant, phosphorus, have not come down in many rivers in the past decade — and are actually rising in several, officials say.
Phosphorus is one of two pollutants blamed for causing algae blooms and "dead zones" in the bay, where fish and shellfish can't get enough oxygen in the water. Plants and animals need phosphorus and nitrogen to live, but the bay is choking on an overdose.
The lack of progress in reducing phosphorus is a particular problem on the Delmarva Peninsula, officials say, where there's evidence it is washing off the many farm fields fertilized with chicken manure. But phosphorus levels also are on the rise in some urban and suburban watersheds, which scientists say may stem from the erosion of stream banks caused by storm runoff from buildings and pavement."