NOT FOR NAVIGATION. Independent public-data side project; not an official USACE or NOAA product. Survey-date conditions only; coverage varies. Software notices

Great Lakes Soundings (public eHydro)

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Survey footprints Survey markers (zoomed out) Soundings (depth, ft LWD) Shoreline (NOAA CUSP) Hex bins (H3, zoomed out) NOAA Charts (ENC) not for navigation

Survey count Newest survey

Basemap

Survey type

Survey year

Depth (ft below LWD)

Color by survey age

Data: USACE eHydro public hydrographic survey data, Buffalo District (CELRB) and Detroit District (CELRE). Depths are feet below Low Water Datum (LWD, IGLD 1985), positive down. Surveys show conditions on the survey date only.

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Built with open-source tools only (MapLibre GL JS, OpenFreeMap / OpenStreetMap, Python + pyproj). No Esri software or basemaps.