Coldwater Lake is a mesotrophic lake in Isabella County, Michigan. Water quality is graded B based on 1 sampling years through 2023. Water clarity is improving over recent sampling years. The lake supports 1 documented fish species including Lake herring. Public access is available. Compared to the 1 other monitored lakes in Isabella County, Coldwater Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2023-06-14. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 10 ft. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Coldwater Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Coldwater Lake
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +3.9 m/yr | 3 |
| Chlorophyll-a | ↓ Declining | +0.45 µg/L/yr | 2 |
Location & Depth Map
Free interactive depth-contour map of Coldwater Lake, reaching a maximum surveyed depth of 65 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
County Ranking
Ranked #2 of 2 lakes in Isabella County
Cleaner Lakes Within 30 Miles
Coldwater Lake holds Grade B. 3 nearby lakes hold higher grades.
Nearby Lakes in Isabella County
Explore Coldwater Lake across LakeGrade
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Isabella County
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its grade
Moderate nutrients, good water quality
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Other Grade B Lakes in Michigan
Clare County · Clarity: 11.5 ft
Clare County · Good
Clare County · Good
Mecosta County · Clarity: 11.5 ft
Mecosta County · Clarity: 10 ft
Clare County · Clarity: 7.5 ft
Mesotrophic Lakes in Michigan
More records, surveys & data sources
EPA Impairment Status
Coldwater Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040802020204-07 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Coldwater Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Mdoc-Statewide MS4Statewide · 3.2 mi away · NPDES MI0057499Recent violation
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-06-14
Monitoring stations: 1