As a first step toward reaching their goal of stopping all releases of chemical pollutants into Chesapeake Bay, Maryland, Pennsylvania, and the District of Columbia are signing an agreement today to clean up toxic “hot spots” in three tributaries of the bay and to curb the flow of chemicals running into the bay’s watershed. The plan will work to reduce the amount of pollutants running into the bay from factories and power plants, and to prevent oil and metal residues from streaming off new streets, rooftops, and developments. Participation by industry and local governments will be voluntary. Meanwhile, after one of the worst crabbing seasons in years, Maryland and Virginia are considering new limits on blue crab harvesting in order to leave 20 percent of the breeding stock in Chesapeake Bay each year.