The Downieville-Nevada City mule deer herd winters in the western foothills of the Sierra Nevada range. The winter range includes dense conifer and oak woodland that is shared with a resident portion of the herd on a mix of public and private lands. In the spring, the herd migrates north and east of Nevada City on both sides of the middle fork of the Yuba River, staying north of Interstate 80, to high-elevation summer range along the crest of the Sierra Nevada. The summer range is primarily mixed conifer habitat opening up to high alpine granite near the crest of the Sierra Nevada. The population size is unknown due to limited survey capacity, but the population is considered stable to declining, affected primarily by dense overstory, environmental stressors, and habitat loss. This GPS collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Due to the small sample size, additional migration routes and winter ranges probably exist beyond the extent of our model output. These mapping layers show the location of the winter ranges for mule deer (Odocoileus hemionus) in the Downieville-Nevada City population in California. They were developed from 10 sequences collected from a sample size of 8 animals comprising GPS locations collected every 1-13 hours.