Officials from the EPA and seven jurisdictions in the Bay watershed (Virginia, Maryland, Pennsylvania, the District of Columbia, West Virginia, Delaware and New York) last year agreed to make sharp nutrient reductions in the amount of the nutrients nitrogen and phosphorus, as well as sediment, that enters the Bay.

The nutrient goals were based on computer models that estimated the levels of reductions needed to attain new water quality criteria in the Bay. The new criteria are intended to protect the broad range of habitats for fish, shellfish and other aquatic life in the Bay.

Maximum nutrient and sediment loads were set for each Bay tributary, and for each jurisdiction within that tributary. The jurisdictions have been working on writing cleanup plans, known as tributary strategies, for their portion of each river.

Excessive amounts of nutrients cause algae blooms that cloud the water and block sunlight from underwater grass beds, which provide habitat for fish, blue crabs and a host of other species. When the algae die, they sink to the bottom and are decomposed in a process that depletes the water of oxygen, creating a summertime “dead zone” in the Bay.

Excess sediment blocks sunlight from grass beds and smothers habitat for bottom-dwelling organisms that form the base of many Chesapeake food webs.