California Groundwater Conditions Update – Spring 2021 California’s drought and groundwater

This report uses maps to depict how groundwater levels have changed over time using two different analytical methods. One method, groundwater level change maps, show the change in groundwater levels between two different springtime measurements. The second method uses trend analysis of water levels for wells having at least 10 annual springtime measurements over a 20-year period to illustrate the statistical magnitude and direction of groundwater level change (a well’s water level increasing or decreasing trend over time). Spring groundwater level data are an important indicator of groundwater conditions because spring generally corresponds to both the pre-irrigation season and the peak groundwater levels in a water year.