Portage Lake is a productive, nutrient-rich eutrophic lake in St. Joseph County, Michigan. Water quality is graded D based on 1 sampling years through 2022. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Chestnut lamprey, Common shiner, and Rainbow darter. Public access is available. Compared to the 12 other monitored lakes in St. Joseph County, Portage Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2022-09-14. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 4.5 ft. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.5 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Portage Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Portage Lake
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.835 m/yr | 3 |
Location
County Ranking
Ranked #8 of 13 lakes in St. Joseph County
Cleaner Lakes Within 30 Miles
Portage Lake holds Grade D. 3 nearby lakes hold higher grades.
- AFishers Lake North Central Basin; Park TownshipSt. Joseph County · 5 mi · Two grade letters higher (D → A)
- BIndian Lake Central Basin; Brady TownshipKalamazoo County · 7 mi · Two grade letters higher (D → B)
- BBarton Lake West Basin; Schoolcraft TownshipKalamazoo County · 3.5 mi · Two grade letters higher (D → B)
Nearby Lakes in St. Joseph County
Explore Portage Lake across LakeGrade
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Fish species and best lakes in St. Joseph County
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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Other Grade D Lakes in Michigan
Eutrophic Lakes in Michigan
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-09-14
Monitoring stations: 1