The Chesapeake Bay remains at risk, largely because of pollution from stormwater runoff, farms and wastewater treatment plants. Excess nitrogen and phosphorous from these sources deplete oxygen and create large “dead zones” in which algae blooms cut off sunlight vital to the survival of marine life and underwater grasses. In December 2010, the U.S. Environmental Protection Agency developed a bay-wide “pollution diet” that sets numeric limits on the total maximum daily load of nutrients each state in the watershed can contribute to the bay. Blue Plains already is meeting the phosphorous limit set for 2015.