A report from UC Davis finds 96 percent of the nitrate pollution in California's Tulare Lake Basin and Salinas Valley comes from farmland -- mostly leeching from fertilizers applied to crops. Nitrates pose a health concern for about a quarter of a million people, many of whom live in California's poorest communities.
UC's California Institute for Water Resources Director Doug Parker:
"Currently there's a real problem of safe drinking water-- and we need to fix that system, and we need to do that quickly. But separately from that is how do we make sure we don't continue to have this problem in the future."
Paul Martin of Western United Dairymen says dairy farmers in the area are voluntarily paying to take part in a new groundwater monitoring program:
MARTIN: "Nobody likes more regulations, but when we implemented this program of representative monitoring, we have over 95 percent of the dairymen signed up, and it's voluntary."
Monitoring groundwater pollution levels is the first step in figuring out which methods of spreading manure on crops lead to the least amount of run-off.