Hypoxia can cause stress or death in bottom-dwelling organisms that cannot move out of the hypoxic zone. The amount of fertilizer entering the Gulf can be determined by examining data from the USGS streamflow and water-quality monitoring stations throughout the Mississippi River basin. USGS scientists, as members of the Committee on Environment and Natural Resources of the National Science and Technology Council, are analyzing current and historic data from these stations to understand better the causes and consequences of hypoxia in the Gulf. The USGS, in cooperation with the Maryland Department of the Environment, the Metropolitan Washington Council of Governments, and the Virginia Department of Environmental Quality, is also studying the amount of nutrient pollution that enters the Chesapeake Bay each year from its major tributaries. Excessive phosphorus runoff has long been recognized as associated with eutrophication of lakes and other nonflowing bodies of water.
Eutrophication is the response of a body of water to enrichment by nutrients.
The results include heavy growth of aquatic plants and algal mats and deoxygenation. Although industrial and sewage discharges of phosphate have been reduced greatly during the past 25 years, eutrophication remains a major environmental issue. Most phosphorus enters bodies of water through soil erosion from agricultural lands. Fertilizer production also is an environmental concern. For every ton of phosphoric acid produced, five tons of phosphogypsum are generated.