Nitrate contamination in drinking water poses a health risk for one tenth of rural Californians, according to a new study by researchers at the University of California- Davis.
Released during National Groundwater Awareness Week, the report, entitled “Addressing Nitrate in California’s Drinking Water,” and commissioned by the California State Water Resources Control Board, is the first comprehensive investigation of nitrate contamination in the Tulare Lake Basin, which includes Fresno, Bakersfield, and the Salinas Valley.
Nitrogen in organic and synthetic fertilizers has increased crop production in California, but excess nitrate in groundwater from surface nitrogen poses serious health risks and has been linked to thyroid illnesses, some cancers and reproductive problems, researchers said.
The study area of 40 percent of California’s irrigated cropland includes four of the nation’s top five counties in terms of agricultural production and represents more than half of the state’s confined animal farming industry.
For the study, UC Davis scientists examined data from wastewater treatment plants, septic systems, parks, lawns, golf courses and farms and found that more than 90 percent of human-generated nitrate contamination of groundwater in these basins is from agricultural activity.
Researchers found that 10 percent of the 2.6 million people who live in the Tulare Lake Basin and Salinas Valley rely on groundwater that may exceed 45 milligrams per liter, the nitrate standard set by the California Department of Public Health for public water systems. And, they say, the problem is likely to worsen in years to come.
Roughly 17 percent of the residents in the Tulare Lake Basin and 10 percent of residents in the Monterey County portion of the Salinas Valley live below the poverty line.
“First and foremost, this is about getting safe drinking water to people,” the report co-author Thomas Harter of the UC Davis Department of Land, Air, and Water Resources, said in a statement. “In the intermediate and long-term, it’s about fixing the source of the problem.”
