Nitrates in California's water, study finds CENTRAL VALLEY

Polluted drinking water in some of California's most productive agricultural areas is putting hundreds of thousands of people at risk for disease and cancer, according to a study released Tuesday by UC Davis.

The report, commissioned by the State Water Resources Control Board, found that 10 percent of the 2.6 million people in the Tulare Lake Basin and Salinas Valley drink groundwater that may contain high levels of nitrates from fertilizers.

The problem is likely to worsen over the next few decades as excess nitrogen applied to crops continues to slowly percolate through the soil into the groundwater, the study said.

"This is a safe drinking water issue," said Thomas Harter, a groundwater hydrologist for the UC Davis Department of Land, Air and Water Resources and the lead author of the report. "Nitrate contamination will be an issue for years to come."

The report, "Addressing Nitrate in California's Drinking Water," is the most comprehensive scientific investigation of nitrate contamination ever done in the area, which includes Fresno and Bakersfield and extends all the way to the edge of Monterey. Scientists examined data from wastewater treatment plants, septic systems, parks, lawns, golf courses and farms in four of the nation's five largest agricultural producing counties. The region contains nearly 4 million acres of farmland - 40 percent of California's irrigated cropland and more than half of the state's confined animal farming industry.

The report found that 254,000 people living in the area rely on groundwater that may exceed the nitrate standard of 45 milligrams per liter set by the California Department of Public Health. More than 90 percent of the contamination comes from farms, ranches and crops, the report concluded.

The findings are disturbing, not only because nitrates in groundwater have been linked to cancer, thyroid and reproductive problems, especially in infants, but because there is no easy solution. Harter said it would cost between $20 million and $35 million every year for decades to treat drinking water and fix systems. The costs could increase over time as more nitrates work their way into the water table.

"This is a very serious matter," said Danny Merkley, director of water resources for the California Farm Bureau. "As a representative of farmers and ranchers, we acknowledge that we have some responsibility to address it and we have already begun doing that."

Merkley said nitrate applications to crops have leveled off since the late 1980s and early 1990s, while crop yields have increased dramatically, meaning farmers are producing more with less.

The problem, according to the report, is that synthetic fertilizer, increased manure applications and a shift from pasture-raised to confined dairy cattle has increased the overall nitrate load.

Besides contaminating groundwater, human-produced nitrogen and nitrates have also been blamed for causing marine "dead zones" and contributing to climate change.

"Growers need to buck up and face the reality that their pollution is harming the environment and jeopardizing the health of tens of thousands of residents," said Steve Shimek, the executive director of the Otter Project, which believes agricultural runoff has contributed to sea otter die-offs.

"I think there will be a push for new regulations and legislation," Merkley said. "Unfortunately, that seems to be everyone's response to this, but over the last 20 years we have shown that we are able to address these issues ourselves without a regulatory hammer."

The study, which was mandated by legislation passed in 2008, concluded that it would not be feasible to remove nitrates from groundwater basins. Instead, it recommends taking measures to improve fertilizer management and treatment systems.