Grass Lake
Grass Lake in St. Joseph County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7 ft visibility. Surface area: 28.2 acres.
- Clarity
- 7 ft
- Area
- 28 acres
- Public access
- Yes
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Why Grass Lake 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 Grass Lake, 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.
Grass Lake is a 28-acre lake in St. Joseph County, Michigan. The lake supports 6 documented fish species including Bluntnose minnow, Fathead minnow, and Finescale dace. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2018-09-11. Grade methodology: LakeQuality methodology.
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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 Grass Lake
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 7 ft. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Grass Lake
Compare lakeside cabins, hotels, and vacation rentals near Grass Lake in St. Joseph 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 Grass Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 28 acres |
| Public Access | Yes |
No bathymetric survey has been published for Grass Lake, so its depth is not documented here.
Recreation & Access
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Grass Lake
EPA Impairment Status
Grass Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040500010808-02 · Official waterbody report · Matched by proximity (2 km)
Graded lakes near Grass Lake
Grass Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in St. Joseph County
Frequently asked questions about Grass Lake
Where is Grass Lake?
- Grass Lake is a lake in St. Joseph 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 Grass Lake?
- Grass Lake in St. Joseph County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7 ft visibility. Surface area: 28.2 acres.
Is Grass Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Grass Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What fish are in Grass Lake?
- Fish species found in Grass Lake include Bluntnose minnow, Fathead minnow, Finescale dace, Green sunfish, Smallmouth bass, Western banded killifish. Grass Lake is located in St. Joseph County, Michigan.
Are there boat ramps on Grass Lake?
- Grass Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Public access is listed as yes.
Explore Grass Lake across LakeQuality
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Where this data comes from
13 measurements from 1 monitoring station, 2018. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS13 samples · 2018
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
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory