UC Davis

Groundwater provides 40–60% of California's water supply. However, domestic wellwater quality is not regulated in California due to its decentralized nature and high cost of testing. Many well water users rely on regional groundwater monitoring data (e.g. Groundwater Ambient Monitoring and Assessment) for information about their water quality but there remains a need for an integrated approach that combines place-based quantitative analysis with cancer risk assessment and community engagement. Our pilot study aims to build relationships and science literacy with private well water users through compensated community sampling of California well water and provision of quantitative reports including 22 inorganic constituents (e.g. lead, arsenic, nitrate) with primary and secondary MCLs. Additionally, the pilot study seeks to investigate the impacts of seasonality, land use, and climate change phenomena (e.g. wildfire, drought, floods) on well water quality. Participants (n=113) were recruited in collaboration with our community partner, the Environmental Justice Coalition for Water. Chemical analyses were performed at UC Davis and used to generate water quality reports and to assess potential public health risks and resources for remediation (see Figure A6 in Appendix). Of the 113 well samples tested, 14 (12.4%) had at least one constituent exceedance of Primary Maximum Contaminant Levels (MCLs), 74 (64.5%) had at least one constituent exceedance of Secondary MCLs, and all had at least one constituent exceedance of Public Health Goals (PHGs) and Notification Levels (NLs) (e.g. Lead (57/57), Uranium (28/57), Arsenic (12/57), Cadmium (11/57)). This study will help study participants assess the health risks associated with consumption of their well water and provides the infrastructure to scale up to a larger community-based groundwater quality monitoring program.