Updated 9 Oct 2026, 3:01 am EDT. Get alerts for Lake Thumb
National Weather Service; National Interagency Fire Center; U.S. EPA CyAN satellite; Michigan DHHS; Michigan DNR. Weather, warnings, fires and satellite refresh when you open the page (checked at most hourly).
Michigan DNR survey, fetched 7 Oct 2026. Not for navigation.
511 acres · deepest 152 ft (measured) · shoreline about 7.4 mi · clarity about 17 ft
Lake Thumb is the 3rd largest of the 39 named lakes of 10 acres or more in Charlevoix County. By Michigan DNR survey it is the deepest of the 22 with a measured depth. Its water is clearer than 29 of the other 30 lakes in the county with satellite clarity readings. Its shoreline measures about 7.4 miles along the state outline. About 10% of its area is deeper than 80 ft.
Ranks against Charlevoix County lakes in Michigan hydrography, Michigan DNR lake surveys and Michigan EGLE satellite clarity; shoreline measured from the state outline. How we measure
1 public access site on Lake Thumb.
Michigan DNR boating access, fetched 7 Oct 2026.
Average water clarity is about 17 ft (Secchi depth 5.1 m, satellite readings 2018–23).
Michigan EGLE satellite clarity, fetched 7 Oct 2026.
Michigan DNR survey; straight-line miles.
Lake Thumb is 152 feet at its deepest point, measured by Michigan DNR survey. It covers 511 acres.
Yes. 1 public access site is listed: Thumb Lake.
About 68% of the lake's area is deeper than 10 feet, measured from Michigan DNR depth contours.