California’s Eroding Water Reliability

In order for California to meet the water needs of its citizens, ecosystems and businesses, the state must take advantage of opportunities to both reduce demand and implement sustainable water supply policies.

Climate Change

Snowpack is vital for the State, as it serves as a natural water banking system that releases water throughout the year. Climate change has not only shifted the timing of snow melt such that there is less water runoff in summer and early fall months, but also has affected the amount of snowpack. The California Department of Water Resources (DWR) reports an expected loss of at least 25% of Sierra snowpack by 2050, which is equivalent to 4.5 million acre feet of water – enough for 9 million households per year. See more about climate change and water policy.

Source: The California Department of Water Resources, Progress on Incorporating Climate Change into Management of California’s Water Resources, 2006 (PDF).

Delta Decline

The Sacramento-San Joaquin Delta forms the eastern portion of the San Francisco Bay estuary and receives runoff from over 40% of California’s land area. Providing critical habitat for many species, it also is the hub of water deliveries in the State, servicing urban, industrial, and agricultural, demands. Recent dramatic declines in several fish species dependent on the Delta emphasize the need to restore habitat, water quality, and adequate in-channel flows for improved ecosystem functioning.

Source: The California Department of Water Resources, State Water Project Delivery Reliability Report (PDF).


Millions of Californians rely on groundwater for all or part of their water supply. Unfortunately, decreasing groundwater quality threatens the security and safety of this water supply. According to the State Water Resources Control Board, over 8,000 public drinking water wells have been shut down since 1984 – in most cases due to contamination. Groundwater contamination currently leaves more than 100,000 Californians without access to clean, safe drinking water in their communities.

Source: State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) program.