Island Lake
Gladwin County, Michigan40 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- #5 of 5 in the county
- 25 ft max depth
- Public access
Island Lake in Gladwin County, Michigan has a water quality grade of A (Excellent). Water clarity: 16.5 ft visibility. Phosphorus: 7.5 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 39.5 acres.
- Clarity
- 16.5 ft
- Max depth
- ~25 ft est.
- Area
- 40 acres
- Type
- Mesotrophic
- Phosphorus
- 7.5 µg/L
- Chlorophyll-a
- 2.4 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Island Lake’s letter
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Island Lake is a 40-acre mesotrophic lake in Gladwin County, Michigan with an estimated average depth of about 25 feet. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 4 other monitored lakes in Gladwin County, Island Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-11. Grade methodology: LakeQuality methodology.
What Island Lake is good for
From access and monitoring records, not editorial picks.
- Clear water16.5 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. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Crystal clear, you can see 16.5 ft down. Phosphorus 7.5 µg/L. Chlorophyll-a 2.4 µg/L. TSI 36. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.5 ft | Not graded |
| Phosphorus | 7.5 µg/L | Good |
| Chlorophyll-a (Algae) | 2.4 µg/L | Good |
| Trophic State Index (TSI) | 36 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~25 ft est. |
| Average Depth | ~8 ft est. |
| Surface Area | 40 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Michigan has not published bathymetry for Island Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Island Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.87 m/yr | 3 |
| Phosphorus | ↓ Declining | +2.6 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.2 µg/L/yr | 2 |
County Ranking
Ranked #5 of 5 lakes in Gladwin County
Nearby Lakes in Gladwin County
Frequently asked questions about Island Lake
Where is Island Lake?
- Island Lake is a lake in Gladwin County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Island Lake?
- Island Lake in Gladwin County, Michigan has a water quality grade of A (Excellent). Water clarity: 16.5 ft visibility. Phosphorus: 7.5 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 39.5 acres.
Is Island Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Island Lake?
- No published bathymetric survey covers Island Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 25 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 39.5 acres.
Explore Island Lake across LakeQuality
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Where this data comes from
22 measurements from 1 monitoring station, 2019–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS22 samples · 2019–2023
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
Lake size & watershed from HydroLAKES (HydroSHEDS)