Just water? Environmental justice and drinking water quality in California's Central Valley

Preliminary policy reports have found that California counties with higher rates of poverty and greater percentages of people of color have a disproportionate rate (i.e. almost twenty-fold higher) of violations of the Safe Drinking Water Act (SDWA). Such reports suggest a case of environmental injustice in these communities. There is little rigorous research on the intersection of drinking water quality, environmental justice (EJ) and environmental health at the community scale in California. We examine the relationship between race, class, and exposure to drinking water contaminants and SDWA violations in community water systems (CWS) in the entire San Joaquin Valley (SJV). Combining datasets on water quality monitoring results, drinking water violations, CWS characteristics and customer demographics, we test two hypotheses: 1) CWS that serve a higher proportion of people of color and/or low-income residents (vs. those that serve higher proportions of whites or high income customers) have higher concentrations of contaminants; and 2) these CWS also have higher rates of SDWA violations. We use a combination of hierarchical, longitudinal and logistic models to focus on arsenic and nitrates. Our hierarchical model of a pilot county within the SJV indicates that for nitrates, race is more significant (p<.001) than income in predicting concentration levels and violation rates. Neither race nor income is a significant predictor for arsenic. Thus nitrates support an EJ hypothesis, but arsenic does not. These findings suggest that California's drinking water laws are not equally protective, and that water policy reforms should focus on this issue.