The map of California shows groundwater level conditions across the state by comparing the most recent measurements at wells to the previous 10 years of measurements for the wells. Most wells are only measured twice a year, in the spring and fall.

The website allows viewers to query information (precipitation, temperature, reservoirs, streamflow, groundwater, snowpack, soil moisture, and vegetation conditions) on maps and show user-defined boundary areas of interest (HUC-8 watersheds, counties, water agencies, groundwater sustainability agencies, or drinking water providers).

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1 Million Acre Feet (MAF). On average, California receives about 200 million acre-feet of water per year in the form of rain and snow. One acre-foot of water is enough to serve two families of four for a year.

National Weather Service (NWS) California Nevada River Forecast Center (CNRFC), quantitative precipitation forecast map

2025年1月15日 · The California Hydrology Update is a regular summary of current weather conditions in the State of California and serves as a supplement to the data on the . California Water Watch website. It is produced by the California Department of Water Resources Hydrology Section and Sustainable Groundwater Management Office teams.

California has an extensive system of federal, state, and local water infrastructure for managing surface water and transporting it to the places where it is used (see map below).

Individual water suppliers may use criteria such as rainfall/runoff, amount of water in storage, decline in groundwater levels, or expected supply from a water wholesaler to define their water supply conditions.

Simplified information on statewide water level conditions is available at DWR’s California Groundwater Live website which summarizes information for more than 6,000 wells. Clicking on a dot on the California Water Watch website’s groundwater map will open a pop-up with available data for that well.

The California Hydrology Update is a regular summary of current weather conditions in the State of . California and serves as a supplement to the data on the California Water Watch website. It is produced by the California Department of Water Resources Hydrology Section and Sustainable Groundwater Management Office teams.