On October 13, 2020 a survey of Upper Letts Lake was conducted where both bathymetric and terrestrial lidar data were collected. Additionally, six bed material samples and three core samples were collected to understand the characterization of the grain-size of the lake bed. Survey data were merged with an additional lidar dataset from the USGS 3DEP program to create digital elevation model (DEM). The DEM was used to update the stage-storage and stage-surface area tables for the reservoir. This data release provides the following data sets; 1) bathymetric and terrestrial elevation data, 2) Combined bathymetric and 3DEP DEM, 3) stage-storage and stage-surface area tables from DEM, and 4) bed material grain-size and loss of ignition results (percent organics). Results show that the storage for the Upper Letts Lake is 377 acre-feet with a surface area of 34.5 acre at the elevation of the spillway outlet. Bed material samples show that the median diameter of the bed ranges from 0.044 to 0.094 mm, with the organic content ranging from 39 to 61 percent. Core samples show that the median diameter of the near-bed strata ranges from 0.868 to 1.342 mm, with the organic content ranging from 8 to 17 percent. For bed material samples, the average gravel, sand, silt, and clay percentages were 0%, 52%, 41%, and 7%, respectively. For core samples, the average gravel, sand, silt, and clay percentages were 61%, 26%, 12%, and 1%, respectively.