This bathymetric dataset provides an update to the stage-storage relation for Little Rock Reservoir located in the Angeles National Forest, California. Bathymetric data was collected using a multibeam echo sounder to provide near-complete coverage and was merged with U.S. Geological Survey 3D Elevation Project lidar to compute a digital elevation model (DEM) of the reservoir and surrounding watershed. The DEM was used to computed storage and surface area for a range of stage elevations. Results show that the mean cross-spillway elevation was 3273 feet above the North American Vertical Datum 1988 (NAVD88) and the mean dam crest elevation was 3277 feet (NAVD88). At the spillway elevation the storage was 3335.8 acre-feet with a surface area of 101.7 acres. At the crest elevation the storage was 3765.6 acre-feet with a surface area of 112.7 acres.