This data release provides access to an aeromagnetic survey over a part of northern California, an area that includes the cities of Portola, California, and Reno, Nevada. The survey extends across the northern part of the Sierra Nevada from Honey Lake in the north to Lake Tahoe in the south and over parts of the Sierra Nevada foothills. These data were acquired between March 3 and May 3, 2021, by EDCON-PRJ, Inc., working under contract to the U.S. Geological Survey. The nominal flying height was based on a best fit, pre-planned, three-dimensional draped surface targeted at 305 m above terrain, subject to aircraft climb and descent limitations. Steep terrain in parts of the survey area required significant departures locally from the pre-planned drape surface (as much as 1207 m), and therefore variable terrain clearance should be considered when modeling and interpreting these data. Flight lines were spaced 800 m apart and directed N88E; tie lines were spaced 8000 m apart and directed N178E. A total of 23,298 line-kilometers were acquired over an area of approximately 16,675 square kilometers. The details of the Portola aeromagnetic survey are described in the document Portola_Tech_Report_508.pdf available for download in this data release. This report was prepared by EDCON-PRJ, Inc., and has not been edited.