Saint Mary'S River Offshore Lake
Chippewa County, WisconsinMesotrophic
Saint Mary'S River Offshore Lake is a mesotrophic lake in Chippewa County, MI. Water quality is graded A based on 2 sampling years through 2025. Compared to the 17 other monitored lakes in Chippewa County, Saint Mary'S River Offshore Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2025-10-15. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
No clarity data. Phosphorus level: 17.5 µg/L. Chlorophyll-a: 1.8 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 17.5 µg/L | A |
| Chlorophyll-a (Algae) | 1.8 µg/L | A |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Location
County Ranking
Ranked #5 of 18 lakes in Chippewa County
Nearby Lakes in Chippewa County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Mecosta County · Clarity: 12.8 ft
Benzie County · Clarity: 13.5 ft
Clare County · Clarity: 15 ft
Kalkaska County · Clarity: 16 ft
Gogebic County · Clarity: 18 ft
Iron County · Clarity: 16 ft
Mesotrophic Lakes in Wisconsin
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-15
Monitoring stations: 1