This mapping documents the changes in extent and condition of vernal pool habitat in the Great Valley between 2005 and 2018. It also inlcudes information based on a 2012 remapping effort. "Vernal pool habitat" is defined as vernal pools and the surrounding upland (typically grassland) habitat matrix. The 2005 basemap was created by using double-blind mapping protocol and included 21.4 million acres in and surrounding the Sacramento and San Joaquin valleys. The area included in the 2012 remapping effort focused on the 807,820 acres identified in the 2005 map and areas immediately surrounding the previously mapped polygons. The area included in the 2018 remapping again focused on previously mapped habitat and surrounding areas. Special attention was paid in counties where habitat has been created through mitigation banking. The result of the 2018 remapping shows 735,820 acres of extant habitat. This is down from 2005, a net reduction of 70,482 acres. Habitat actually was eliminated from 76,023 acres, but these losses were partially off-set by mitigation banks built and by acres that we missed in the original mapping. In the thirteen years since the Recovery Plan was adopted, some 5,848 acres per year on average have been lost.

Creation Date: 
Friday, December 31, 2021
Last Updated: 
Wednesday, March 9, 2022
Type of Data: 
GIS vector dataset
Programs and Focus Areas: 
Environmental Informatics Program
Wetland Monitoring & Assessment
Location Information
General Project Location(s): 
Greater Central Valley
Data Availability
Please Cite This Dataset as: 

Carol W. Witham. 2021. Changes in the Distribution of Great Valley Vernal Pool Habitats from 2005 to 2018. Sacramento, CA. Report prepared for the San Francisco Estuary Institute/Aquatic Science Center in Richmond, CA. Under U.S. EPA Region-9 Wetland Program Development Grant #CD_99T93601.

Terms of Use: 

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More information about GNU General Public License is available at data are available without restriction upon use with the following caveats. Prudent usage, knowledge of the data quality, and professional courtesy should all be considered in obtaining and using SFEI data. As this dataset is NOT a survey document, neither use it as such nor use it beyond the limits of the source scale. Please read and fully comprehend all available metadata prior to data use. SFEI requests that the use of these data in any map, publication, or report should include citation of the data source(s) used and give proper attribution and credit to the originators of the data. Questions about SFEI data may be directed to the GIS Manager, at 510-746-7334.