GEF

Unit 2  |  Water Science and the Water Cycle 55 2.4  Water Pollution Amajor issue in water sustainability is water pollution , a deg- radation of water quality that affects humans and ecosystems alike. Pollutants may be biological, such as bacteria from sew- age, or chemical, such as synthetic agricultural pesticides. Water pollution can also be caused by sedimentation which is excess nutrients, raised water temperature, radioactivity, or altered pH . Scientists categorize water pollution as originating from point sources —confined, identifiable sources such as a factory outflow pipes—or nonpoint sources —diffused sources such as farm fields or urban runoff . Point sources are relatively easy to control through regulations and technical adjustments. In the developed world, point sources have been substantially reduced since the 1970s by laws such as the Clean Water Act in the U.S. However, these laws have been somewhat less suc- cessful at dealing with the challenges of nonpoint sources. Pesticide runoff is a nonpoint water pollution source that often ends up in watersheds. WATER POLLUTION A degradation of water qual- ity due to a range of factors WATER QUALITY The chemical and biological profile of water. SEDIMENTATION An increase in suspended particles in water bodies. pH A measure of the acidity or basicity of a liquid. POINT SOURCE A single or confined source of water pollution, such as a factory outflow pipe. NONPOINT SOURCE A non-specific or dispersed source of water pollution, such as farm fields. RUNOFF Water flowing from a land area, such as a farm field or urban area. CLEAN WATER ACT A U.S. federal law that regulates the discharge of pollutants into the nation’s surface waters.