Michigan Lighthouses

Sources

The lights: Wikipedia’s List of lighthouses in Michigan, which states it is the list as identified by the U.S. Coast Guard. Focal heights cross-checked against the USCG Light List, Volume VII (a federal work, public domain by 17 U.S.C. § 105); positions cross-checked against Wikidata. Ten reviewed corrections are recorded in the build, each citing its source.

The water: depth charts and the shaded lakes on the map above are NOAA Great Lakes bathymetry (public domain). ⚠️ The connecting channels — the St. Marys, St. Clair and Detroit rivers — are drawn from © OpenStreetMap contributors (ODbL) and carry no depth: NOAA’s grid is 93 × 66 m and records a 700 m river as land, so those pixels are a shape, not a survey. Lights on those rivers therefore show no depth figure — a value sampled there would belong to the nearest open lake, up to a mile away, not to the channel the light stands in.

The charts: north up, 4.2 × 4.2 miles, with a one-mile bar. Contour rings are interpolated from NOAA’s grid (one depth every 93 × 66 m), not surveyed lines, and a few charts show a straight seam where NOAA joined surveys of different ages.

The photographs: Wikimedia Commons public-domain and CC0 files, plus Detroit Publishing Co. glass negatives the Library of Congress lists with no known restrictions — we do not publish what we cannot license. Where a light has both an old and a recent photograph, the panel shows both; every year shown is evidenced (the camera’s date, a federal record, an archive caption or the Library of Congress catalog), and a print with no recorded year says “undated”. Each is credited on its own panel.

Michigan Lake Depths is an independent project and is not affiliated with, sponsored by, or endorsed by the U.S. Coast Guard, NOAA, the Michigan DNR, the Library of Congress, or OpenStreetMap. Not for navigation.