Coldwater Lake
Isabella County, MichiganView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · Mercury
- #1 of 2 in the county
Coldwater Lake in Isabella County, Michigan has a water quality grade of A (Excellent). Water clarity: 11 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 1 µg/L.
- Clarity
- 11 ft
- Typical in September
- 56°F
- Type
- Oligotrophic
- Phosphorus
- 16 µg/L
- Chlorophyll-a
- 1 µg/L
- Trend
- ↑ Improving
Stays via Stay22
Stays near Coldwater Lake
Compare lakeside cabins, hotels, and vacation rentals near Coldwater Lake in Isabella 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 Coldwater Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Michigan’s top lakes →
Watch Coldwater Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Coldwater Lake is a cold, clear oligotrophic lake in Isabella County, Michigan. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. The lake supports 1 documented fish species including Lake herring. Compared to the 1 other monitored lakes in Isabella County, Coldwater Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-14. Grade methodology: LakeQuality methodology.
What Coldwater Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11 ft of visibility
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Coldwater Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11 ft. Phosphorus 16 µg/L. Chlorophyll-a 1 µg/L. TSI 39. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | 16 µg/L | Good |
| Chlorophyll-a (Algae) | 1 µg/L | Good |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Water Temperature
Coldwater Lake typically sits around 56°F at the surface in September. Summer average is about 54°F. Usually warmest in Aug (about 56°F) and coldest in May (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 479 field readings (2021–2023) via the EPA Water Quality Portal. See the full Coldwater Lake water temperature breakdown →
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Coldwater Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.831 m/yr | 5 |
| Phosphorus | ↑ Improving | -0.47 µg/L/yr | 5 |
| Chlorophyll-a | → Stable | 0 µg/L/yr | 4 |
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 · Matched by proximity (0.75 km)
County Ranking
Ranked #1 of 2 lakes in Isabella County
Nearby Lakes in Isabella County
Frequently asked questions about Coldwater Lake
Where is Coldwater Lake?
- Coldwater Lake is a lake in Isabella County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Coldwater Lake?
- Coldwater Lake in Isabella County, Michigan has a water quality grade of A (Excellent). Water clarity: 11 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 1 µg/L.
Is Coldwater Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Coldwater Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
What is the water temperature of Coldwater Lake?
- Coldwater Lake typically sits around 56°F at the surface in September, from 479 EPA Water Quality Portal field readings (2021–2023). That is a typical value for the month, not a live reading.
What fish are in Coldwater Lake?
- Fish species found in Coldwater Lake include Lake herring. Coldwater Lake is located in Isabella County, Michigan.
Explore Coldwater Lake across LakeQuality
Fish species and top-graded lakes across Michigan
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
Michigan's cleanest and most-polluted lakes, ranked
More Michigan Lake Rankings
Other Grade A Lakes in Michigan
Oligotrophic Lakes in Michigan
Where this data comes from
70 measurements from 1 monitoring station, 2018–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS70 samples · 2018–2023
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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