Laserfiche WebLink
<br />001[155 <br /> <br />IRRIGATION AND WATER POLLUTION <br /> <br />Of course, to report that agriculture is a principal source of water pollution is not to <br /> <br />indict western irrigation, let alone our irrigation districts. One shortcoming of the several EP A <br /> <br />reports just cited is that they fail to distinguish agricultural runoff and irrigation return flows. <br /> <br />Without question, a significant share of runoff occurs from dryland farming in humid regions, <br /> <br />especially the com belt. Despite this there is reason to attribute serious water poUution to <br /> <br />irrigation practices. In 1984, the EP A reported: <br /> <br />While irrigated farming, too, is a source of sediment, nutrients, and pesticides, it also causes special <br />agricultural pollution problems. Salts and other minerals are carried to water courses by irrigation <br />return flows and to ground water resources by percolation through soil and rock layers. The Soil <br />Conservation'Services (SCS) estimates that half of the 90 to 100 million tons of salt. delivered <br />annually to streams is from agriculture. This can make a significant contribution to salinity <br />downstream, which affects aquatic habitat and downstream water users at great cost. 23 <br /> <br />Most western irrigation states that reported to EP A for the 1988 Inventory 'cited <br />agriculture as a principal pollution source.24 <br /> <br />23 See NPS Report, illll!:lb at 2-9, citing U.S. Dep't of Agriculture, "RCA Potential <br />Problem Area II Water Quality: Problem Statement and Objective Determination" (July 1979). <br /> <br />24 Office of Water, United States Environmental Protection Agency, "National Water <br />Quality Inventory: 1988 Report to Congress" 8-9 (1990); and ~ Economic Research Service, <br />USDA, "Irrigation in the United States," NTIS 85-195568. <br /> <br />30 <br />