San Luis reservoir (IMAGE) American Geophysical Union Caption Water in the San Luis reservoir, which was constructed as a storage reservoir in California’s Central Valley. Groundwater in this region may never be able to recover from past and future droughts, according to a new study published in Water Resources Research. Credit Fredrick Lee Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.