The bathymetric data set was collected in Rock Run on Dec. 10, 2015 by USGS ILWSC staff Clayton Bosch and Louis Pappas. The bathymetric data were collected with an RD Instruments 1200 kHz ADCP (S/N 8617) and Trimble Ag 162 GPS mounted on the M/V La Moine. A temporary reference point (TRP) was established on the north side of the footbridge over the connecting channel to the Des Plaines River. The mean water surface elevation (504.97 feet, WGS 84) during the survey was established from a temporary reference point whose elevation was later established by GPS survey. The measured depths were then converted to a lake bed elevation. The location and depth data were compiled into a bathymetry dataset (Rock Run Bathymetry Data.csv). The dataset was imported as a shapefile into ArcMap (ArcGIS software 10.3.1). A shape file of lake boundary elevation was developed based on imagery from September 16, 2015 (U.S. Department of Agriculture Farm Services Agency National Agriculture Imagery Program (NAIP)) (point data can be found in Rock Run Lake Boundary.csv). This shape file was merged with the elevation shape file to enforced the lake and island edges in the final bathymetry. This elevation shape file was then contoured using Geostatistical Analyst/Deterministic methods/Radial Basis Functions with Completely Regularized Spline (defaults were used except Sector type: 4 Sectors, Angle: 42, Major semiaxis: 800, Minor semiaxis: 500). The raster was then exported to a GeoTIFF file with a resulting raster cell size of 1 foot.