Water Portfolios

The California Water Plan provides an accounting of water that enters and leaves the state and how it is used and exchanged between the regions. This is important to all water planning activities. Water portfolio data provides information for comparison about how water uses and sources of supply can vary between wet, average, and dry hydrologic conditions for each of the California hydrologic regions. The statewide information has been compiled from the 10 California hydrologic regions.

Water Use in California

California’s water supplies vary from place to place, season to season, and year to year. The state’s water users (generally environmental, agricultural, and urban sectors) have variable needs for the quantity, quality, timing, and place of use. The California Water Plan has developed water balances to show how water was used by agriculture and urban sectors or dedicated as environmental water and where water came from to provide that water for individual years from 1998-2015. A statewide average is shown below for years 1998-2015.

Data: Where Does California’s Water Go?

California Water Uses (1998-2005 Average)


  • California’s water supports three main sectors: cities and communities, agriculture, and environment.
  • On average, the proportion of water used by each sector is 10 percent cities and communities, 40 percent agriculture, and 50 percent environment.
  • This statewide ratio varies widely depending upon whether a year is wet or dry. In wet years, the proportion that serves environmental purposes can be 60 percent or more, while in dry years that proportion drops to roughly one-third.
  • Water often serves double duty; water allocated for one purpose is often reused for other purposes downstream.  
  • Water often has multiple benefits across sectors.

Water Supply and Balance Data Interface

As part of DWR's ongoing efforts to document the assumptions, data, analytical tools, and methods used to prepare California Water Plan (CWP) content, DWR has developed the Water Supply & Balance Data Interface; a Microsoft Excel-based data viewer and analysis tool. The Data Interface allows DWR staff and the public to easily access and compare historic water use and supply data published by sector in corresponding Water Portfolio sets. It includes a variety of drop-down menus and tools for assessing various parameter data at various regional levels. Multi-year data for water years 2002 - 2015 have been compiled at the lowest regional levels used in the CWP, the Detailed Analysis Unit (DAU) by County intersection, aggregated through statewide values.

The Data Interface is an Excel-based viewer and analysis tool; make sure to 'Enable Macros' if prompted when opening. Region and data selections are made on the "Interface" sheet, from blue-highlighted cells. Selections can only be made from available values in the menus. Teal-highlighted drop-downs are used to select specific data (e.g., applied or net water use for sector demands) – see "DataParam" for flow-chart of available options. Tables and graphs will automatically update as new regions or data are selected; for a complete "balance" of the selected region, view tables on the "BalExample" sheet. Note, the 'Lite' version of the Data Interface is only for data viewing.

You can download the tool and handout at: Water Supply & Balance Data Interface (Zip)

Related Pages

How to Contact Us

Contact us for more information or questions about the Water Plan Portfolios.