Does Water Quality Improve When a Safe Drinking Water Act Violation Is Issued? A Study of the Effectiveness of the SDWA in California

The Safe Drinking Water Act addresses harmful contaminants in drinking water by providing states the authority to monitor public water systems, notify the public of exceedances above allowable levels, and cite persistent violators. Violating water systems are subject to intense regulatory and public scrutiny. The response of contaminant levels to violation status has not been explored empirically. This paper addresses this relationship through an event study using data on arsenic and nitrate levels in California. I find that violation status has a significant positive effect on nitrate levels post-violation, but no effect on arsenic levels. I also examine the effect of the 2006 arsenic Maximum Contaminant Level revision, finding a discontinuity in contaminant levels at revision. These results suggest that while public disclosure may deter systems from violating, once they go into violation the Public Notification Rule is not effective at encouraging a return to compliance.