CALIFORNIA WATER WATCH
A Snapshot of Hydroclimate and Water Supply Conditions
The Department of Water Resources (Department) makes no warranties, representations or guarantees, either expressed or implied, as to the accuracy, completeness, correctness, or timeliness of the information in the multiple datasets accessible through this data viewer, nor accepts or assumes any liability arising from the use of such information or use of the underlying data. Neither the Department nor any of the sources of the information utilized by this viewer shall be responsible for any errors or omissions, or for the use or results obtained from the use of this information. The Department expressly disclaims any responsibility to defend or indemnify users against claims of others based on users’ copying, reliance, distribution, or other use of any of this information. Material provided herein is for informational purposes only and does not constitute an administrative, regulatory, or statutory determination or finding regarding hydrologic and water supply conditions. Use of the material provided herein does not guarantee the adequacy of any regulatory or statutory compliance document that relies on this material. Boundaries shown in this viewer are graphical representations only, and do not establish legal rights or define legal boundaries.
About This Website
Welcome to the California Water Watch. Here we bring together data from a variety of sources to allow viewers to obtain a quick snapshot of the state’s water conditions at the scale of their local watershed.
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). Watersheds are a fundamental spatial area for assessing local water conditions. Our maps display information at the scale of Hydrologic Unit Code-8 (HUC-8) watersheds. HUC boundaries are defined by the U.S. Geological Survey; a HUC-8 watershed is considered a subbasin of a major river basin. California includes all or part of 140 HUC-8 watersheds. Precipitation and temperature values provided on the website are for HUC-8 watersheds selected by the viewer.
This website only provides data, it does not interpret or characterize the data for regulatory, administrative, or financial assistance purposes. Viewers seeking information about regulatory or financial assistance programs related to hydrologic conditions should consult the website of the specific program to determine the conditions that program uses to determine regulatory requirements or eligibility.
Water Supply Conditions
The water suppliers’ websites identified on the local watershed page may provide more information on your water supply conditions. Please be aware that not all water suppliers may have websites. Some very small water systems and reclamation districts that may serve irrigation water do not have websites. It is not unusual for an address or a point selected on a map to be within the boundaries of multiple local water agencies. In rural areas, for example, a point may fall within the boundaries of a county water agency, an irrigation district, and a public water system (drinking water supplier). Additionally, this website has been designed to display the adjacent water agency if the point selected on the map is immediately adjacent to the boundaries of two water agencies. Viewers should consult their water bills to identify their water provider.
Many factors affect how water is used in California.
How to Use This Website
- Enter your address or click here for a map to select a location. You will be taken to a page showing summary daily precipitation and temperature statistics for your local watershed and the name(s) of local water supplier(s). Data are shown by water year (October 1st through September 30th).
- From this page you may access additional data pages providing information on precipitation and temperature at statewide and regional scales and on reservoir (daily), streamflow (daily), groundwater (semiannual), snowpack (daily), soil moisture (daily), and vegetation (daily) conditions at local scales. Once you are on one of these additional data pages you may access any of the other data pages from there.
- Close the data pages to return to the local watershed page.
A forecasting icon located at the top of all the pages will take you to a page where you can find current precipitation forecasts and links to additional weather forecasting resources.
Depending on hydrologic conditions, special messages on observed conditions may be posted in this box
California is experiencing multi-year dry conditions that began in Water Year 2020 and have triggered state response actions. Links to additional resources are provided below and further background on drought in California is available.
Drought means different things to different water users. Dry conditions turn into drought based on impacts, just as wet conditions may be harmless – until water overtops a levee and inundates a neighborhood or orchard. People and natural systems experience drought differently. Dry conditions can quickly impact ranchers grazing livestock, rural residents relying on private wells, or fish dependent upon small streams. Large urban water agencies with diverse water sources typically can buffer their customers from feeling the effects of multiple dry years.
California Water Watch allows you to see the current hydrologic conditions associated with drought in your local watershed. Local hydrologic conditions help inform state drought response actions, but they are not the only triggering factor for state response. The broader context includes other factors such as water rights administration or special fishery protection measures. Viewers seeking information about applicability of state drought-related regulatory or financial assistance programs to their area should consult drought.ca.gov or the website of the specific program to determine the conditions being used to determine regulatory requirements or eligibility.
Governor’s Emergency Proclamations for Drought
Map of counties covered by a current state-level emergency proclamation
Risk of Drought Impacts
When precipitation is low for an extended period of time, the risk that people and natural systems will feel an impact increases. The risk also increases when the dry conditions are coupled with above-average temperatures, as has been observed in California’s recent droughts. This map shows where precipitation for the water year to date is below 70 percent of average and temperatures are in the 80th percentile or above (warmer than 80 percent of the recorded temperatures, or unusually hot). Precipitation and temperature represent minimum thresholds of risk applicable to all water uses, whether urban, agricultural, or environmental. Some water users (such as large urban water agencies) can mitigate this risk by relying on surface and groundwater storage and other resources, but multi-year persistence of these conditions will eventually affect most water users and the environment.
California is transitioning to a warmer climate where extended dry periods are expected to become more common. The historical experience of drought as an occasional occurrence is being replaced by this new normal.
Hydrologic conditions associated with risk of drought impacts evolve slowly, and impacts may linger after rain and snow returns and hydrologic conditions improve. Groundwater storage, for example, may be slow to recover and trees killed by drought may contribute to wildfire risk in subsequent years.
Federal Drought Monitor
The U.S. Drought Monitor is created weekly by the University of Nebraska, U.S. Department of Agriculture, and National Oceanic and Atmospheric Administration. It is a subjective blend of information drawn from a variety of sources. USDA uses it to identify agricultural producers’ eligibility for federal financial assistance programs. The U.S. Drought Monitor is not intended to characterize local water supply conditions; its website recommends that “decision makers adopt an operational definition of drought for their own circumstances, incorporating local data such as grazing conditions or streamflow at a nearby gauge.”