Gage Lake is a productive, nutrient-rich eutrophic lake in Cass County, Michigan. Water quality is graded F based on 1 sampling years through 2024. Compared to the 22 other monitored lakes in Cass County, Gage Lake ranks #23 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2024-05-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
No clarity data. Phosphorus level: 90 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 90 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Gage Lake
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Fishing Gage Lake
Water Temperature
Gage Lake averages about 71°F at the surface in summer, usually warmest in Aug (about 73°F) and coldest in Feb (about 39°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 775 field readings (2013–2025) via the EPA Water Quality Portal. See the full Gage Lake water temperature breakdown →
Location
County Ranking
Ranked #23 of 23 lakes in Cass County
Cleaner Lakes Within 30 Miles
Gage Lake holds Grade F. 2 nearby lakes hold higher grades.
Nearby Lakes in Cass County
Explore Gage Lake across LakeGrade
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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 F Lakes in Michigan
Van Buren County · Very Poor
Berrien County · Clarity: 3 ft
Berrien County · Clarity: 3 ft
Allegan County · Clarity: 3 ft
St. Joseph County · Clarity: 3 ft
St. Joseph County · Clarity: 3 ft
Eutrophic Lakes in Michigan
More records, surveys & data sources
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Gage Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Dowagiac WwtpDowagiac · 4.2 mi away · NPDES MI0022837MajorRecent violation
- Alliance Cloud Services Llc-GwcuDowagiac · 2.5 mi away · NPDES MI0003069Recent violation
- Service Oil Co-DowagiacDowagiac · 3.8 mi away · NPDES MI0054488
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-05-23
Monitoring stations: 1