This data represents the watersheds that supply water to the surface drinking water sources (rivers, reservoirs, lakes, etc.) in California. 82% percent of the water supplied by public water districts for domestic and other uses in California comes from rivers, lakes, reservoirs, and other surface water sources (Kenny et al. 2009). The quality of the water flowing into these sources is directly affected by the condition of the land in the surrounding watershed (Lenat and Crawford 1994, Gutman 2007). Better quality water generally translates to lower filtration and treatment costs for the utilities who deliver water to homes and businesses. California’s drinking water supply system relies on approximately 157 million acres of land spanning 8 states to collect, filter, and deliver water.Mapping the watersheds that supply drinking water is important to highlight areas where more land‐use protection and habitat restoration is needed. Increasing conservation action in unprotected watersheds could protect and in some cases improve drinking water quality, reducing the need for costly and energy intensive filtration and treatment facilities (adapted from Klausmeyer K. and K. Fitzgerald. 2012. Where does California’s water come from? Land conservation and the watersheds that supply California’s drinking water. A Science for Conservation Technical Brief. An unpublished report of The Nature Conservancy. San Francisco, CA.)

This data represents the watersheds that supply water to the surface drinking water sources (rivers, reservoirs, lakes, etc.) in California. 82% percent of the water supplied by public water districts for domestic and other uses in California comes from rivers, lakes, reservoirs, and other surface water sources (Kenny et al. 2009). The quality of the water flowing into these sources is directly affected by the condition of the land in the surrounding watershed (Lenat and Crawford 1994, Gutman 2007). Better quality water generally translates to lower filtration and treatment costs for the utilities who deliver water to homes and businesses. California’s drinking water supply system relies on approximately 157 million acres of land spanning 8 states to collect, filter, and deliver water.Mapping the watersheds that supply drinking water is important to highlight areas where more land‐use protection and habitat restoration is needed. Increasing conservation action in unprotected watersheds could protect and in some cases improve drinking water quality, reducing the need for costly and energy intensive filtration and treatment facilities (adapted from Klausmeyer K. and K. Fitzgerald. 2012. Where does California’s water come from? Land conservation and the watersheds that supply California’s drinking water. A Science for Conservation Technical Brief. An unpublished report of The Nature Conservancy. San Francisco, CA.)