Lake Gratiot
Lake Gratiot in Keweenaw County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 16.5 ft visibility. Maximum depth: 70 ft. Surface area: 1453.1 acres.
- Clarity
- 16.5 ft
- Max depth
- 70 ft
- Area
- 1,453 acres
- Trend
- → Stable
- Public access
- Yes
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Free interactive depth-contour map of Lake Gratiot, reaching a maximum surveyed depth of 70 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
Why Lake Gratiot has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Lake Gratiot, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Gratiot is a 1,453-acre lake in Keweenaw County, Michigan with a maximum depth of 70 feet. Water clarity is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-13. Grade methodology: LakeQuality methodology.
Watch Lake Gratiot water quality
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Gratiot
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 16.5 ft down. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Lake Gratiot
Compare lakeside cabins, hotels, and vacation rentals near Lake Gratiot in Keweenaw 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 Lake Gratiot
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Planning a trip? Cabins and lodging at Lake Gratiot → · more Michigan lake trips
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 70 ft |
| Surface Area | 1,453 acres |
| Public Access | Yes |
Recreation & Access
- Gratiot LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Gratiot
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.868 m/yr | 7 |
| Phosphorus | ↓ Declining | +0.54 µg/L/yr | 7 |
Graded lakes near Lake Gratiot
Lake Gratiot has no grade, but these lakes within a short drive do.
Nearby Lakes in Keweenaw County
Frequently asked questions about Lake Gratiot
Where is Lake Gratiot?
- Lake Gratiot is a lake in Keweenaw County, Michigan. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Lake Gratiot?
- Lake Gratiot in Keweenaw County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 16.5 ft visibility. Maximum depth: 70 ft. Surface area: 1453.1 acres.
Is Lake Gratiot safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Gratiot is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Lake Gratiot?
- Lake Gratiot has a maximum depth of 70 feet. The lake covers 1453.1 acres.
Are there boat ramps on Lake Gratiot?
- Lake Gratiot has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Gratiot Lake. Public access is listed as yes.
Explore Lake Gratiot across LakeQuality
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Where this data comes from
72 measurements from 1 monitoring station, 2016–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS72 samples · 2016–2022
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory