High-Resolution Bathymetry of the Southern Portion of Lake Calumet, Cook County, Illinois, June 2023

These data are high-resolution bathymetry (lakebed elevation) of the southern portion of Lake Calumet in Cook County, Illinois, acquired from a hydrographic survey on June 30, 2023. This dataset is provided as American Society for Photogrammetry and Remove Sensing (ASPRS) compressed LAS (*laz) files, a standardized binary format for storing three-dimensional point cloud data as a series of x (longitude), y (latitude), and z (elevation) points and attributes (ASPRS, 2011). This survey utilized a multibeam echosounder mapping system (MBMS), which consists of a multibeam echosounder (MBES) and an internal navigation system (INS) mounted on a marine survey vessel. Data were collected as the vessel traversed the lake along overlapping longitudinal survey lines. Data collection software integrated and stored the depth data from the MBES, along with the horizontal position and vertical attitude data of the vessel from the INS in real time. Proprietary computer software was used to post-process bathymetry data from the real-time data files for final export. The northern portion of the lake, characterized by shallower depths, was surveyed using a single-beam echosounder in July 2023; those data are available within this data release but are not included in the compressed LAS files.

The bathymetric dataset, provided in ASPRS compressed LAS format as "LakeCalumet_MBES_20230630_fullres.laz," represents the data at its full resolution obtained during data collection with minimal cleanup to preserve as much detail as possible. Any edits made to the dataset were focused on removing obvious outliers clearly distinguishable from genuine bathymetric details. Please note that the full-resolution dataset is large and may not be readily viewable without specialized software. A reduced-resolution version of the full dataset was created featuring a nominal 0.5-meter (m) point spacing to enhance accessibility and usability. This downscaled dataset is provided in ASPRS compressed LAS format as "LakeCalumet_MBES_20230630_reducedres.laz".