California’s San Joaquin Valley is one of the oldest and most extracted oil and gas basins in the US. For decades, state law has allowed water extracted during oil and gas production, known as produced water, to be disposed of in unlined pits. On October 21, 2021 PSE Senior Scientist Dr. Dominic DiGiulio provided a technical briefing and overview of the findings of PSE’s peer-reviewed study on the effects of unlined produced water ponds on groundwater resources in the Tulare Basin.