Thumb Lake
Charlevoix County, Michigan508 acresView mapDirections
EGLE publishes the water-quality measurements for Thumb Lake. Here is what has been measured.
- Impaired · Mercury
- 152 ft max depth
- Public access
- Limited data
Thumb Lake in Charlevoix County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 17 ft visibility. Maximum depth: 152 ft. Surface area: 507.5 acres.
Free interactive depth-contour map of Thumb Lake, reaching a maximum surveyed depth of 152 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
Thumb Lake is a 508-acre lake in Charlevoix County, Michigan with a maximum depth of 152 feet. The lake supports 3 documented fish species including Blacknose shiner, Rock bass, and Smallmouth bass. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-08-26. Methodology: how these readings are compared.
Thumb Lake covers about 510 acres in Charlevoix County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Thumb Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Thumb Lake is good for
From access and monitoring records, not editorial picks.
- Clear water17 ft of visibility
- Boat launch1 documented ramp
- Fishing3 species recorded
- Deep water152 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Thumb Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Thumb Lake is safe to swim in today is a call for the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Thumb Lake
These are the measurements EGLE publishes for Thumb Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 17 ft down. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 17ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Thumb Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
152 ft
Surface area
508 acres
Public access
Yes
Listed by EGLE
Lake Size & Watershed
Watershed (drainage) area
8 sq mi
HydroLAKES / HydroSHEDS
Shoreline
6.1 mi
HydroLAKES / HydroSHEDS
Elevation
1,033 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Thumb LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Thumb Lake
Compare lakeside cabins, hotels, and vacation rentals near Thumb Lake in Charlevoix County, Michigan — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Thumb Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
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Follow Thumb Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Thumb Lake
EPA Impairment Status
Thumb Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040700040103-04 · Official waterbody report
Nearby Lakes in Charlevoix County
Frequently asked questions about Thumb Lake
Where is Thumb Lake?
- Thumb Lake is a lake in Charlevoix County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Thumb Lake?
- Thumb Lake in Charlevoix County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 17 ft visibility. Maximum depth: 152 ft. Surface area: 507.5 acres.
Is Thumb Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Thumb Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
How deep is Thumb Lake?
- Thumb Lake has a maximum depth of 152 feet. The lake covers 507.5 acres.
What fish are in Thumb Lake?
- Fish species found in Thumb Lake include Blacknose shiner, Rock bass, Smallmouth bass. Thumb Lake is located in Charlevoix County, Michigan.
Are there boat ramps on Thumb Lake?
- Thumb Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Thumb Lake. Public access is listed as yes.
Can I fish at Thumb Lake?
- Thumb Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Michigan's fish and wildlife agency, so check its current regulations before you go.
Explore Thumb Lake across LakeQuality
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Where this data comes from
13 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS13 samples · 2022
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory