California Population Trends by Geography
The datasets provide population estimate trends from 1998 to the current year for each of California’s 58 counties, further disaggregated by Detailed Analysis Units (DAUs) - the smallest geographic units historically used by the California Department of Water Resources for water planning as part of the California Water Plan. DAUs are subdivisions of Planning Areas and often align with county boundaries, although a single DAU may span multiple counties. They have traditionally supported water demand estimates based on crop and land use types. Within this dataset, two data tables are provided: 1) A table showing [population trends by county and DAU](https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/751d4f96-7881-488b-9401-28fd32649c39), and 2) A table showing [population trends by county, DAU, and places]( https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/ce6e2a05-bbed-4fbe-80e4-91400e175727) The population estimates in these tables were developed using U.S. Census 2000, 2010, and 2020 data, along with California Department of Finance (DOF) intercensal estimates. The county‑DAU table uses DOF July county totals, while the county‑DAU‑places table uses DOF January place totals. DOF produces population estimates twice each year—January and July. January estimates are available at the level of census places within each county, whereas July estimates are produced at the county level. As a result, county totals differ between the two due to six months of natural change (births, deaths, migration) and because January estimates incorporate preliminary vital statistics that are finalized in the July series. Throughout development, intermediate results were reviewed and adjusted as needed, applying professional judgment to smooth trends where appropriate. Since the California Water Plan is retiring DAUs as its planning and analysis framework, future updates to this dataset will transition away from DAU based geography. Instead, population estimates will be provided based on other geographic units, such as the 8-digit Hydrologic Units (HUC8) defined by the U.S. Geological Survey’s Watershed Boundary Dataset. A [dashboard](https://tableau.cnra.ca.gov/#/site/DWR_Planning/views/County_DAU_Places_Pop_Trends/JanuaryPopbyPlacesforacountyandayear?:iid=1) is available for visualizing population trends by county and DAU and places. Please note that county-DAU-places values reflect DOF January estimates, while County-DAU values reflect DOF July estimates.
Data files
| Data title and description | Access data | File details | Last updated |
|---|---|---|---|
County/DAU Population Trends Annual Data The datasets provide population estimate trends from 1998 to the current year for each of California’s 58 counties, further disaggregated by Detailed Analysis Units (DAUs) - the smallest geographic units historically used by the California Department of Water Resources for water planning as part of the California Water Plan. DAUs are subdivisions of Planning Areas and often align with county boundaries, although a single DAU may span multiple counties. They have traditionally supported water demand estimates based on crop and land use types. Within this dataset, two data tables are provided: 1) A table showing [population trends by county and DAU](https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/751d4f96-7881-488b-9401-28fd32649c39), and 2) A table showing [population trends by county, DAU, and places]( https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/ce6e2a05-bbed-4fbe-80e4-91400e175727) The population estimates in these tables were developed using U.S. Census 2000, 2010, and 2020 data, along with California Department of Finance (DOF) intercensal estimates. The county‑DAU table uses DOF July county totals, while the county‑DAU‑places table uses DOF January place totals. DOF produces population estimates twice each year—January and July. January estimates are available at the level of census places within each county, whereas July estimates are produced at the county level. As a result, county totals differ between the two due to six months of natural change (births, deaths, migration) and because January estimates incorporate preliminary vital statistics that are finalized in the July series. Throughout development, intermediate results were reviewed and adjusted as needed, applying professional judgment to smooth trends where appropriate. Since the California Water Plan is retiring DAUs as its planning and analysis framework, future updates to this dataset will transition away from DAU based geography. Instead, population estimates will be provided based on other geographic units, such as the 8-digit Hydrologic Units (HUC8) defined by the U.S. Geological Survey’s Watershed Boundary Dataset. A [dashboard](https://tableau.cnra.ca.gov/#/site/DWR_Planning/views/County_DAU_Places_Pop_Trends/JanuaryPopbyPlacesforacountyandayear?:iid=1) is available for visualizing population trends by county and DAU and places. Please note that county-DAU-places values reflect DOF January estimates, while County-DAU values reflect DOF July estimates. | Download | CSV | 10/21/25 |
County/DAU/Places Population Trends Annual Data The datasets provide population estimate trends from 1998 to the current year for each of California’s 58 counties, further disaggregated by Detailed Analysis Units (DAUs) - the smallest geographic units historically used by the California Department of Water Resources for water planning as part of the California Water Plan. DAUs are subdivisions of Planning Areas and often align with county boundaries, although a single DAU may span multiple counties. They have traditionally supported water demand estimates based on crop and land use types. Within this dataset, two data tables are provided: 1) A table showing [population trends by county and DAU](https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/751d4f96-7881-488b-9401-28fd32649c39), and 2) A table showing [population trends by county, DAU, and places]( https://data.cnra.ca.gov/dataset/population-trends-by-geography/resource/ce6e2a05-bbed-4fbe-80e4-91400e175727) The population estimates in these tables were developed using U.S. Census 2000, 2010, and 2020 data, along with California Department of Finance (DOF) intercensal estimates. The county‑DAU table uses DOF July county totals, while the county‑DAU‑places table uses DOF January place totals. DOF produces population estimates twice each year—January and July. January estimates are available at the level of census places within each county, whereas July estimates are produced at the county level. As a result, county totals differ between the two due to six months of natural change (births, deaths, migration) and because January estimates incorporate preliminary vital statistics that are finalized in the July series. Throughout development, intermediate results were reviewed and adjusted as needed, applying professional judgment to smooth trends where appropriate. Since the California Water Plan is retiring DAUs as its planning and analysis framework, future updates to this dataset will transition away from DAU based geography. Instead, population estimates will be provided based on other geographic units, such as the 8-digit Hydrologic Units (HUC8) defined by the U.S. Geological Survey’s Watershed Boundary Dataset. A [dashboard](https://tableau.cnra.ca.gov/#/site/DWR_Planning/views/County_DAU_Places_Pop_Trends/JanuaryPopbyPlacesforacountyandayear?:iid=1) is available for visualizing population trends by county and DAU and places. Please note that county-DAU-places values reflect DOF January estimates, while County-DAU values reflect DOF July estimates. | Download | CSV | 02/25/26 |
Supporting files
| Data title and description | Access data | File details | Last updated |
|---|---|---|---|
Dashboard of Population Trends by County, Places and DAU The dashboard, created using Tableau, provides a graphical representation of population trends by county, places and DAU. | WEBSITE | 03/27/26 | |
DAU County Shapefile DWR subdivided California into study areas for planning purposes. The largest study areas are the ten hydrologic regions (HR), corresponding to the State’s major drainage basins. The next levels of delineation are the Planning Areas (PA), which in turn are composed of multiple detailed analysis units (DAU). The DAUs are often split by county boundaries, so are the smallest study areas used by DWR. The DAU/counties are used for estimating water demand by agricultural crops and other surfaces for water resources planning. Under current guidelines, each DAU/County has multiple crop and land-use categories. Many planning studies begin at the DAU or PA level, and the results are aggregated into hydrologic regions for presentation. This is considered a legacy dataset and will no longer be updated. After decades of use, Detailed Analysis Units are being retired as the framework dataset for the California Water Plan. Future updates of the California Water Plan will use the 8-digit Hydrologic Units of the U.S. Geological Survey’s Watershed Boundary Dataset as the planning and analysis framework. | 07/18/25 |