United States Environmental Protection Agency Office of Water (WH-556F), Office of Wetlands, Oceans, and Watersheds (A-104 F) EPA843-F-93-001C March 1993 WETLANDS FACT SHEET #3 Consequences of Wetland Loss and Degradation The lost or degradation of wetland* can lead to serious consequences, including increased flooding; species decline, extinction or deformity; and decline in water quality. The following ait* few examples oftkeconseauences of wetlands loss and degradation* 12000 10000 8000 £000 4000 2000 0 I I I I I I I I I I I I SPECIES DECLINE Populations of mallard and northern pin- tail ducks in North America have declined since 1955 (see graph above). The loss and degradation of wetlands is one of the major causes for the de- cline in certain waterfowl popu- lations. For ex- ample, in the US. prairies in 1990, mallard duck populations reached their lowest recorded number. The well-being of wa- terfowl popula- tions is tied directly to the status and abundance of wetland habitats. Waterfowl populations have reached record lows in recent years. Sim- ply said, as wetlands go, so go waterfowl. SPECIES DEFORMITY Wetlands in the Kesterson National Wildlife Refuge in California's Central Valley weredegradedafter being continuously flooded with agricultural irrigation return flow waters that contained high concentrations of selenium. Large-mouth and striped bass and catfish dis- appeared from Kesterson National Wildlife Ref- uge in 1982. In the spring of 1983, eggs from water birds at the site hatched less frequently and had more deformities in the embryos. Cost estimates for the refuge cleanup and restoration of its wetlands now exceed $5 billion. Decline in Duck Populations: 1955 -1991 Source Office of Migratory Bird Management Population ' ii mm i m Section, USFWS FLOODING Based on a study comparing parts of the Charles River in Massachusetts with and with- out wetlands, it was determined that the loss of 8,422 acres of wetlands within the Charles River Basin would have pro- duced an annual flood damage of over $17 million. For this reason, the US Army Corps of Engineers elected to preserve wetlands rather than con- struct extensive flood control facili- ties for this portion of the Charles River near Boston. WATER QUALITY Forested riparian (streamside) wetlands play an important role in reducing nutrient loading into water bodies such as the Chesa- peake Bay. In one study, a riparian forest in a predominantly agricultural watershed was shown to remove approximately 80% of the phosphorus and 89% of the nitrogen from the water before entering a tributary of the Chesa- peake Bay. Destruction of wetlands that reduce the amount of nutrients entering the Bay would lead to an increase of undesirable weed growth and algae blooms. When these algal blooms decompose, large amounts of oxygen are used up, depriving fish and other aquatic organisms of the oxygen needed for survival. Algal blooms are a major cause of fish kills. For more information, contact the EPA Wetlands Hotline at 1-800-832-7828 * contractor operated ------- |