Sidescan sonar images and substrate classification maps for the Mississippi River below Lock and Dam No. 2 in Minnesota, August 2025

Recreational-grade sidescan sonar offers a rapid and cost-effective method for imaging benthic environments, and recent advances in image processing techniques have shown promise for producing automated, reproducible substrate maps from sonar imagery. To investigate potential suitability of substrates for lake sturgeon spawning habitat, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (USACE) St. Paul District, collected sidescan sonar imagery of the Mississippi River bed below Lock and Dam No. 2, near Hastings, Minnesota. Data were collected on August 21, 2025 for a study area covering approximately 33 hectares. Raw sidescan data were processed into georeferenced images using the open‐source software PING‐Mapper (Bodine et al., 2022, 2024). PING-Mapper was also used to perform an automated substrate classification from the sidescan data, identifying the following classes: fines flat, fines ripple, cobble/boulder, hard bottom, and wood. Additionally, sonar returns were processed to produce a dataset of water depths at each ping location.

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