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Davis, California

Wednesday, May 29, 2024

High nitrate levels in drinking water concerning for rural Californians

The Tulare and Salinas Basins – home to half of California’s cow population and 40 percent of its irrigated agricultural land – are vital assets to the state of California. But the area also possesses a significant threat to its 2.6 million residents, and until now most of them were unaware of it.

A recent report compiled by researchers at UC Davis investigated the safety of drinking water in the Tulare and Salinas Basins. The study was performed in response to state legislation passed in 2008 requiring a detailed examination of nitrate levels in the Tulare Lake Basin, which includes Fresno and Bakersfield, and the Salinas Valley, which includes Salinas and areas near Monterey.

“These are two areas that have a history of pretty high nitrate contamination in their ground water,” said George Kostyrko, director of the Office of Public Affairs at the California State Water Resource Control Board.

According to the report, “Addressing Nitrate in California’s Drinking Water,” they found that one in 10 people living in these areas were at risk of exposure to harmful levels of nitrate contamination. These people rely on groundwater that may exceed the nitrate standard of 45 milligrams per liter, which was set by the California Department of Public Health for public water works.

Jay Lund, professor of Civil and Environmental Engineering at the UC Davis Center for Watershed Sciences and co-author of the report, said this problem is likely to continually worsen in the coming decades.

“It takes, on average, between five and 30 years for the nitrate that enters the surface to make its way into our drinking water. So, given that long time delay, it would take a very, very long time for that nitration to no longer exist in the groundwater,” Lund said.

According to Lund, the study focused on where the nitrates are coming from and what we can do to reduce levels. Researchers examined data from wastewater treatment plants, septic systems, parks, lawns, golf courses and farms.

Significantly, agricultural fertilizers and animal manure applied to cropland are the two largest regional sources of the nitrate that leaks into the ground water, making up more than 90 percent of the total.

Since the 1940s, the use of nitrogen in organic and synthetic fertilizers has substantially increased crop production in California but at a considerable cost. Nitrate from the surface nitrogen has continually leaked into groundwater.

Although the report did not go into detail about the effects of nitrate consumption on human health, according to the press release, there is an understanding among the medical community that nitrate intake has been linked to thyroid illnesses, some cancers and reproductive problems.

As a result, the study looked into finding solutions to reduce nitrate levels in the short term to provide safe drinking water to residents of Tulare and the Salinas Basin. In the long term, the researchers hope to continually reduce nitrate levels by improving and possibly changing fertilizer management and water treatment.

“It’s not a one-size-fits-all solution. The more promising options are going to be location-specific,” said Thomas Harter of the UC Davis Department of Land, Air and Water Resources and co-author of the report. “The type of water source, the agricultural practices of that area and the proximity of the communities to the contaminated water are all key parts to finding a solution.”

Now that the report is finished, the California State Water Board will be conducting a public workshop on May 23 to discuss the findings and solutions outlined in the report with the public.

“Our role after the public workshop will be to look at the report and public comments and put together a report ourselves to submit to the state water board with specific recommendations,” said Kostyrko.

Lund concluded that California, because of its strong agricultural industry, will always have a problem with nitrate contamination, but the main goal is to reduce this problem and provide safe drinking water.

CLAIRE MALDARELLI can be reached at science@theaggie.org.


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