FRESNO, Calif. (AP) -- State water regulators have adopted an order for farmers to monitor and clean up groundwater in California's Central Valley, home to some of America's most contaminated aquifers.
The order, adopted by the Central Valley Regional Water Quality Control Board on Thursday, affects about 7,200 growers in the Tulare Lake basin -- including parts of Fresno, Tulare, Kings and Kern counties -- who farm on about 3 million acres of irrigated farmland.
It's the second order adopted by the board. The first was adopted for the eastern San Joaquin region, and the board is poised to adopt a half dozen orders for other parts of the region.
A total of 35,000 famers and 7 million acres of irrigated land will eventually be affected by the orders.
The new rules cover not only groundwater but also surface water, which has been regulated on an interim basis since 2003.
Nitrate contamination of groundwater is a pervasive problem in California's agricultural heartland and is bound to intensify in coming years, according to a University of California, Davis, study released last year. The nitrates pollute drinking water for more than 1 million Californians in the Salinas Valley and parts of the Central Valley.
Chemical fertilizers and livestock manure are the main source of nitrate contamination. And nitrate leaching from agricultural land is responsible for 96 percent of current groundwater contamination, according to the study.
And while fertilizer use has leveled off in recent years, the amount of dairy manure has increased, making for a net increase over the past decade in nitrates loaded into the ground.
At least 3 million acres of agricultural land have potential problems with nitrates in groundwater, water officials said.
Under the new rules, existing farmer-run coalitions will do the monitoring and reporting of ground and surface water. Each farmer will go through an evaluation and identify practices to protect water quality. Farms deemed most susceptible to problems will undergo additional monitoring, have to craft a management plan and take steps to address the pollution.
Farmers say the new rules are expensive and bureaucratic, though state water regulators estimate implementation will cost less than $2 per acre. Farmers also say they have worked to change their farming practices to address the problem, by using new technologies that measure how much fertilizer, if any, the soil needs.
Environmental groups say the proposed regulations are too weak, because they don't hold individual farmers responsible and the board has no regulatory authority over the coalitions.
