But loss of important farmlands is not our country's only natural resource concern. Agriculture is the Nation's biggest user of water, accounting for nearly 83 percent of our total water consumption. Our large ground water resources are being depleted in some areas at a rate of 21 billion gallons a day, with no recharge taking place. In some areas of Arizona, ground water levels are falling 7 to 10 feet a year. The quality of our water is another problem area.
Agriculture is the most widespread cause of nonpoint source pollution.
Runoff increases the levels of sediment, infectious agents, nutrients, and pesticides in our streams. Irrigation return flows generally increase the level of dissolved solids, nutrients, and pesticides. And irrigation also is responsible for increased salinity as water seeps through the soil and picks up salt from the underlying mica shale deposited on ancient sea beds. Flooding on land adjoining rivers, streams, and lakes is another concern. About 54 million acres of our prime farmlands are in flood-prone areas.