PUB00111 - Laserfiche WebLink

Home Browse Search

Problems Nonpoint source pOllution is generated where land and water meet. As a result, the historic and modern uses of an area define the contaminants, the pathways those contaminants take to the water, and ultimately may dictate the solutions used to sepa. rate the two. The State Board lists the most prevalent sources of pollution in California rivers and streams, in order of their occurrence, as agriculture. limber harvests, mining operations and urban runoff. AGRICULTURE One of the largest land uses in California. and as a result one of the largest sources of pollutants, is agriculture. Problems result from the tilling of soil, from the application of fertilizers and pesticides and from the discharge of used irrigation water. Runoff usually carries away soil, which contains natural and applied phosphorus and nitrogen - nufrients that encourage algae growth. The soil itself KESTERSONITULARE BASIN When Kesterson Reservoir was closed in the late 1980s the problem of farm drainage poisoning waterfowl at the refuge was solved. But the problem of what to do with tainted runoff was not. Flushing westside farm fields of excess salts is essential to continued agricultural production. With Kesterson closed, farmers in the Westlands Water District have turned to on-farm efforts to reduce the amount of drainage produced. In the Tulare Lake Basin agricultural drainage flows into more than 7,000 acres of evaporation ponds. The ponds, however, also have been a problem for wildlife as selenium, arsenic, molybdenum, and other trace elements concentrate to high levels as the water evaporates. Wildlife studies at the ponds have found a high rate of deformed embryos. The Central Valley Regional Water Quality Control Board has required the pond own- ers to remedy the problems. In 1990, the multi-agency San Joaquin Valley Drainage Program determined that as much as 75,000 acres of land that generated the worst drainage might have to come out of irrigated pro- 8 can stay suspended in the current. reducing the photosynthesis that grows microscopic organisms that feed larger organisms. Farm runoff also carries pesticides. State agriculture officials estimate that more than 200 million pounds of 440 different pesticides are used in California each year on the state's crops, and enough of that gets into streams for the State Board to consider pesticide contamj. nation to be a common cause of impairment to rivers. California still is dealing with the consequences of banned, but persistent pesticides, such as dichloro. diphenyl-trichloroethane, or DDT. Some of these chemicals pollute and repollute the environment as they cycle through wildlife. Other persistent chemicals, such as dibromochloropropane, or OBCP, are still making their way into groundwater, even though their use has been discontinued. But California also faces problems from contempo. rary chemicals, some of which are extremely toxic, if only for a shari time. Tests In Central Valley streams after heavy rains have found significant levels of diazinon, an insecticide used in orchards and around homes. Samples drawn from the Feather, Sacra- duction. The Central Valley Project Improvement Act of 1992 authorized the U.S. Bureau of Reclamation (Bureau) to begin buying up some of those parcels as part of a land retirement program. But the focus has shifted back to the historic solution - a Delta drain. The Bureau built 85 miles of a drain that was to carry the farm waste to the Della, before environmental and economic concerns stymied the project in 1975. Kesferson lies af one end of the partially built drain. It received the runoff until the poisoning was detected, the drain was closed and the search began for another solution. A group of farmers sued to force the drain to be completed, and in 1994 a federal court judge in Fresno sided with the growers, ordering the Bureau to apply for a permit to discharge the waste into fhe Delta. The case was appealed and settlement talks included both environ- mentalists and urban water districts whose supply could be degraded by the compfeted drain. Meanwhile, the Bureau has opened 28 miles of the existing drain to bypass the agricultural drainage around existing wildlife refuges in the San Joaquin Valley.