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<br />menta and Mokelumne river watersheds and in the <br />Imperial Valley have contained farm chemicals at <br />concentrations toxic to test organisms as high as 30 <br />percent of the time. Samples taken from the San <br />Joaquin River by the Central Valley Regional Water <br />Quality Control Board have been toxic up to 50 per- <br />cent of the time - raising concern that pesticides <br />may playa greater role than previously thought in <br />California's declining fisheries. <br /> <br />While some farm chemicals are washed from fields <br />by rain, other pollutants are flushed out by irrigation <br />water. California has 9.5 million acres of irrigated <br />land and about one in three of these acres, mostly <br />in the San Joaquin and Imperial valleys, must be <br />routinely flushed to remove excess salts and other <br />elements that can reduce crop yields. While the <br />flushing process protects crop and soil productivity, <br />it creates drainage water tainted with toxic levels of <br />both farm chemicals and naturally occurring <br />elements. <br /> <br />A dramatic example of this problem was the wildlife <br />deformities discovered in the early 1980s at <br />Kesterson Reservoir near Los Banos, where ponds <br />and sloughs were filled with irrigation runoff tainted <br />with salts and selenium. While the refuge has been <br />closed, the problem of what to do with the polluted <br />runoff has not been resolved. <br /> <br />In California's hill country, cattle and sheep graze <br />on more than 40 million acres. Much of that land is <br />high in the watersheds, where pOllution can create <br /> <br /> <br />problems for miles of streams and much of the <br />societal water supply. Animals directly degrade water <br />quality by congregating in streams during the dry <br />season - trampling banks and increasing the <br />sediment load. When they defecate into streams, <br />the grazing animals spread pathogens that flow for <br />miles downstream. Grazing animals also indirectly <br />diminish water quality by reducing vegetation - <br />increasing runoff and erosion. <br /> <br />m:a:r- <br /> <br />Few pollution problems have <br />proven to be as intractable as <br />those created by abandoned <br />mines. Nationally, EPA blames <br />mining for 10 percent 01 all <br />water quality problems. In the <br />West, where hard rock mining <br />was more prevalent and where <br />many mines long ago became <br />unprofitable and were aban- <br />doned, the problem is even <br />greater. <br /> <br />California has more than 15,000 <br />abandoned mines - 160 of them <br />are known to discharge acidic <br />waste and 20 of those mines are <br />considered major environmental <br />hazards. Mine waste is a par- <br />ticularly severe problem on <br />many Sierra and north coast <br />streams. And mine waste often <br />contaminates groundwater, as <br />well as streams. <br /> <br />Tons of copper. :::.inc and Olher <br />metals from Iron JHoulllain <br />Mine, (lbm'e, routim'(\' washed <br />intl' rhe Sacmmellto Rh'er <br />hilore its Superfund <br />desiNl/atioll brought money <br />Will other resources allowing <br />for the colltrol and treatment <br />of this discharge. <br /> <br /> <br /> <br />The Central Valley Regional Water Quality Control <br />Board has found fish from seven Sierra streams <br />to be contaminated with concentrations of mercury <br />exceeding the National Academy of Sciences <br />standards. The mercury was mined in the coastal <br />hills and was used in the Sierra gold fields. It still <br />pollutes streams in both regions. <br /> <br />In addition to gold, miners disgorged from the <br />Sierra silver, cooper and zinc - metals that are <br />now washed from pits, shafts and piles of mine <br /> <br />Finding clll'iroJ11J1('lItally safe \HI.\"S to dispose <br />of the thl'usands of tons of nIl/llure prl'duced <br />each year is a major problem for dairies <br />throughl'ut the state. <br /> <br />9 <br />