A new study conducted by the University of California, Davis, shows that one in 10 people living in California’s most productive agricultural areas are at risk of being exposed to harmful levels of nitrate contamination in their drinking water.

The report, “Addressing Nitrate in California’s Drinking Water,” was commissioned by the California State Water Resources Control Board to study the water in the Tulare Lake Basin, which includes Fresno and Bakersfield and the Salinas Valley.

The study blames agriculture for the majority of nitrate contamination in the groundwater, which includes the use of chemical fertilizers and livestock manure. In their report, UC Davis scientists examined data from wastewater treatment plants, septic systems, parks, lawns, golf courses and farms. The report concludes that more than 90 percent of human-generated nitrate contamination of groundwater in these basins is from agricultural activity.

The nitrate study area includes four of the nation's five counties with the largest agricultural production, representing 40 percent of California's irrigated cropland and more than half of the state's confined animal farming industry.

"Cleaning up nitrate in groundwater is a complex problem with no single solution," said Jay Lund, director of the UC Davis Center for Watershed Sciences and a report co-author. "This report should help inform discussions among people involved with drinking water, waste discharge and agricultural issues, including various local and state government agencies."

In addition to pointing out the scope of the nitrate contamination in the ground water, the report also outlines potential funding solutions to cleaning up the problem. Because it could be costly to fix the problem–estimates run from $20 million to $35 million per year for decades—ways to offset the costs were offered. These include creating a fee or tax on nitrogen fertilizer use, improve farming practices, water blending, treatment or alternative water sources.

If nothing is done, the study concludes, the financial burden on many agricultural communities could increase. By 2050, nearly 80 percent of the population — about 2 million residents — in the study area could have nitrate contamination exceeding the state standard.

The State Water Board will be conducting a public workshop on May 23 to consider public comment, as well as discuss the findings and options outlined in the UC Davis report. The board will review the public comment and issue recommendations to the state Legislature, as called for in the legislation.

The board has posted the documents on the internet for public review and comment here.

Read the study here.