The state-federal Bay Program last year adopted new water quality criteria for the Chesapeake aimed at improving conditions for fish, shellfish, underwater grasses and other resources throughout the Chesapeake.

To attain those criteria, computer models indicate the region’s needs to reduce the amount of nitrogen entering the Bay, estimated at 278 million pounds in 2002, to 175 million pounds. Phosphorus must be reduced from 19.5 million pounds to 12.8 million pounds, and sediment from 5.05 million tons to 4.15 million tons.

The goal is to achieve those reductions by 2010 to meet a court-approved deadline for removing the Chesapeake from the EPA’s list of impaired waters.

The nutrient and sediment reductions were allocated among all of the major rivers feeding the Bay, and among all seven jurisdictions in the watershed: Virginia, Maryland, Pennsylvania, District of Columbia, West Virginia, Delaware and New York. Each jurisdiction either has written, or is in the process of writing tributary strategies that outline the actions needed to reach the goals.

Nutrients foul water quality by spurring algae blooms that block sunlight to underwater grass beds, which provide critical habitat in the Bay. When the algae die, they decompose in a process that depletes oxygen in the water. Sediment contributes to the problem by further clouding the water, and smothering bottom-dwelling creatures.