Drinking water for more than 370,000 Californians is contaminated with arsenic, nitrate, and other chemicals, according to an extensive analysis by researchers at UC Berkeley and UCLA. In many cases, the state’s agricultural industry is to blame.
The study also found that water contamination disproportionately affects communities of color — particularly Latino communities — and researchers warned that their results likely underestimate the extent of the problem. Researchers also released an interactive drinking water tool that Californians can use to research their community’s water quality and hold local representatives accountable.
“I think a lot of people might be surprised to learn that, given how wealthy the state of California is, we still don’t have universal access to clean drinking water,” said Lara Cushing, an assistant professor of environmental health sciences at UCLA and a senior coauthor of the study.
The report is the first comprehensive analysis of California’s water quality and the first to focus on demographic disparities. Researchers collaborated with the California Environmental Protection Agency and the Community Water Center, a nonprofit that works to ensure safe drinking water in farmworker communities. Their work was recently published in the American Journal of Public Health.
Access to clean and affordable drinking water is by law a human right in California, and community water systems are required by federal law to undergo regular testing for contaminants. But according to the study’s authors, about 10% of California’s public drinking water systems are out of compliance with the state’s standards, and many water systems don’t meet federal standards either.
Meanwhile, many rural Californians aren’t connected to community water systems at all. Instead, they rely on private domestic wells that are largely unregulated and that, researchers found, disproportionately suffer from contamination. While less than 4% of Californians get their water from domestic wells, more than 40% of the 370,000 residents affected by contaminated drinking water rely on such wells.
The study analyzed three common contaminants — arsenic, nitrate and hexavalent chromium — though researchers noted there were many more they could have included. Two of the three contaminants are connected to California’s agricultural sector. While arsenic occurs naturally in groundwater, it can become concentrated when the water table is depleted; as California’s drought continues, Central Valley farmers have been overpumping groundwater, which can increase arsenic levels in local water supplies. Nitrate contamination is also connected to agribusiness, the result of fertilizer runoff and industrial animal farming.
Hexavalent chromium is a byproduct of industrial and manufacturing activities that involve wood treatment or metal plating. All three contaminants pose serious health risks, and can increase the risk of cancer and other illnesses.
The authors noted that safeguarding California’s drinking water will only become more urgent as climate change and prolonged drought put additional stress on the state’s water system.