Bathymetry of Bubbly Creek and Chicago Sanitary and Ship Canal Sidings in Cook County, Illinois, July 2023

These data are high-resolution bathymetry (riverbed elevation) in compressed LAS (*.laz) format, generated from the July 17–19, 2023, hydrographic survey of Bubbly Creek and various sidings, harbors, and turning basins on the Chicago Sanitary and Ship Canal (CS&SC) in Cook County, Illinois. The survey includes all Bubbly Creek from the confluence with the CS&SC in the north to the Racine Avenue Pump station in the south; various sidings and turning basins along the CS&SC between Kedzie Avenue and South Halsted Street; and the Marine Safety Station harbor near the Chicago Harbor Lock on Lake Michigan. This survey is a continuation and enhancement of the bathymetric survey of the CS&SC in Cook County, Illinois, conducted August 22–24, 2022 (Huizinga and Rivers, 2023). Hydrographic data were collected using a high-resolution multibeam echosounder mapping system (MBMS), which consists of a multibeam echosounder (MBES) and an inertial navigation system (INS) mounted on a marine survey vessel. Data were collected as the vessel traversed the river along overlapping longitudinal survey lines distributed throughout the reach. Data collection software integrated and stored the depth data from the MBES and the horizontal and vertical position and attitude data of the vessel from the INS in real time. Data processing required specialized computer software to extract bathymetry data from the raw data files and to summarize and map the information. The full-resolution data are provided in American Society for Photogrammetry and Remote Sensing (ASPRS) compressed LAS format as BubblyCr_CSSCsidings_bathymetry_2023-07_fullres.laz. This bathymetry dataset is the full-resolution, near-raw data output from the processing software. This dataset has undergone limited cleanup and editing to remove obvious stray data and aquatic vegetation, but data editing was minimized to retain detail. Furthermore, this dataset is large, and may not be readily viewable without specialized software. The reduced-resolution data also are provided in ASPRS compressed LAS format as BubblyCr_CSSCsidings_bathymetry_2023-07.laz. This bathymetry dataset is a subset of the full-resolution data in the BubblyCr_CSSCsidings_bathymetry_2023-07_fullres.laz file, reduced to a nominal 0.5-meter point spacing. The compressed LAS format is a standardized binary format for storing 3-dimensional point cloud data and point attributes along with header information and variable length records specific to the data. Data points are stored as a 3-dimensional data cloud as a series of x (longitude), y (latitude), and z (elevation) points. Please refer to http://www.asprs.org/Committee-General/LASer-LAS-File-Format-Exchange-Activities.html for additional information. Reference Cited: Huizinga, R.J., and Rivers, B.C., 2023, Chicago River and Chicago Sanitary and Ship Canal Bathymetry in Cook County, Illinois, August 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P94TL2PV.