Drought-related water pollution disproportionately affects California Latino communities: Study

Drought-driven drinking water contamination is disproportionately affecting members of California's Latino communities, a new study has found.

Among the pollutants plaguing these water systems are arsenic and nitrate, which are linked to an increased risk of a variety of diseases, according to the study, published Wednesday in the American Journal of Public Health. Some such illnesses include cancers, cardiovascular diseases, developmental disorders and birth defects.

Oftentimes, community water systems that distribute water with higher contaminant concentrations exist in areas that lack sufficient public infrastructure or sociopolitical and financial support, the authors noted. Meanwhile, drought conditions generally make water sources less dilute, thereby triggering a spike in contaminant concentrations.

The study authors, from the University of California Santa Barbara, analyzed 2007-20 trends in arsenic and nitration concentrations in regional surface and drinking water — employing water sampling data, historical drought records, agricultural intensity and sociodemographic characteristics of local populations.

Ultimately, they found that community water systems serving majority Latino populations consistently showed higher and more variable levels of both pollutants, in comparison to those in systems that predominantly serve other residents.

“Drought increased nitrate concentrations in majority Latino/a communities, with the effect doubling for CWSs with more than 75 percent Latino/a populations served," lead author Sandy Sum, a UC Santa Barbara PhD candidate, said in a statement, using the acronym for community water systems. 

"Arsenic concentrations in surface sources also increased during drought for all groups,” she added.

Zooming in on the specifics of these pollution levels, Sum and her colleagues found that nitrates in groundwater-sourced drinking water increased from 2.5 milligrams per liter in 1998 to a peak of 3.1 milligrams per liter in 2018 for these communities.

In contrast, those in non-majority Latino systems declined from 2.1 to 1.8 milligrams per liter during that same period.

Drought conditions, the researchers determined, exacerbated existing disparities in nitrate concentrations found in surface-sourced drinking water. This specific surge was especially apparent in very small and privately operated community water systems, according to the study.

As far as arsenic is concerned, drought increases the overall concentrations of this contaminate in surface-sourced drinking water for both majority and non-majority Latino communities, the authors found.

Sum surmised that water systems serving largely Latino communities are likely "not mitigating elevated nitrate concentrations during drought conditions, which exacerbates existing disparities."

"This may reflect a lack of treatment infrastructure, resource constraints or other operational or technical differences,” she added, stressing the need for relevant policy initiatives.

Although her research focused on nitrates and arsenic alone, Sum warned that these communities "may also be at increased risk for contamination from other sources like pesticides, waste disposal sites and manufacturing plants, under stressors such as drought, floods and other natural events."