Nitrate contamination in groundwater from fertilizer and animal manure is severe and getting worse for hundreds of thousands of residents in California’s Central Valley farming communities, according to a study released Tuesday by researchers at the University of California, Davis.

Nearly 10 percent of the 2.6 million people living in the Tulare Lake Basin and Salinas Valley might be drinking nitrate-contaminated water, researchers found. And if nothing is done to stem the problem, the report warns, nearly 80 percent of residents could be at risk of health and financial problems by 2050.

High nitrate levels in drinking water are known to cause thyroid cancer, skin rashes, hair loss, birth defects and “blue baby syndrome,” a potentially fatal blood disorder in infants.
The report is the most comprehensive assessment so far of nitrate contamination in California’s agricultural areas.


“The problem is much, much, much worse than we thought,” said Angela Schroeter, agricultural regulatory program manager for the Central Coast Regional Water Quality Control Board, a state water agency.
Nitrate-contaminated water is a well-documented fact in many of California’s farming communities.
The agricultural industry, however, has maintained that it is not solely responsible because nitrates come from many sources. While the report focused on California, nitrates in groundwater is a problem that plagues farming communities around the U.S.
But, according to the UC Davis report, 96 percent of nitrate contamination comes from agriculture, while only 4 percent can be traced to water treatment plants, septic systems, food processing, landscaping and other sources.