Anthropogenic Enviornmental Threats

Up to one-third of the nitrogen that pollutes the Bay and its rivers comes from the air. Sources of air pollution include vehicles, industries, power plants, gas-powered lawn tools, and farm operations. Nitrogen from vehicle exhaust washes into the Bay and contributes to algae blooms. These blooms cloud the water and absorb the oxygen, creating dead zones in the Bay that cannot support underwater grasses, crabs, fish, and other marine life. In addition, roads, parking lots, and other paved surfaces—make erosion and sediment pollution worse in the Bay. Air pollution, primarily from power plants, is also the main source of the mercury that contaminates fish in the Bay watershed. As a result, anglers are warned to limit their consumption of certain fish species due to potentially harmful levels of this toxic chemical. EPA recently proposed regulations to limit air pollution from the nation’s coal-fired power plants, however the damage has already been done. Surface run-off is also a source of damage to the ecosystem. When it rains, water accumulates on man-made surfaces such as roads, roofs and parking lots. These hard (impervious) surfaces prevent the rain from soaking in. As more houses, roads, and shopping centers are built, more water runs off the surfaces and enters our streams and other waterways, either directly or through urban storm drain systems, in the estuary. Storm water carries a host of contaminants from the land into the water: sediment, phosphorus, nitrogen, toxic metals, herbicides and pesticides, organic material, oil compounds, and bacteria. Roadways, for example, release oil and grease, tailpipe emissions, and other toxics from motor vehicles. Lawns contribute fertilizer and animal waste. Construction sites release quantities of mud. Sediment keeps sunlight from reaching underwater grasses. As these plants die, the animals that rely on them are imperiled. Storm water pollution is responsible for about 19 percent of the nitrogen and phosphorus pollution in the Bay, if the contribution of nitrogen from air pollution is included. It is one of the major reasons that the Bay remains on the EPA's "dirty waters" list. Those aren't the only things that storm drains bring in to the estuary. Toxic chemicals are constantly entering the Chesapeake Bay and its tributaries via wastewater, agriculture, storm water and air pollution. While chemicals such as DDT and PCBs have been banned from production for years, many chemical contaminants are still widely used or persist in the environment. There are many groups and projects (many state run) that are dedicated to cleaning and restoring the Chesapeake Bay Estuary.