Loon Lake
Loon Lake in Iosco County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 23 ft visibility. Maximum depth: 128 ft. Surface area: 416.6 acres.
- Clarity
- 23 ft
- Max depth
- 128 ft
- Area
- 417 acres
- Trend
- → Stable
- Public access
- Yes
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Why Loon Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Loon Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Loon Lake is a 417-acre lake in Iosco County, Michigan with a maximum depth of 128 feet. Water clarity is declining over recent sampling years. The lake supports 1 documented fish species including Lake herring. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2018-09-07. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Loon Lake
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 23 ft down. Trophic State Index: 32.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 23 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Loon Lake
Compare lakeside cabins, hotels, and vacation rentals near Loon Lake in Iosco 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 Loon Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 128 ft |
| Surface Area | 417 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Long LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Loon Lake
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.465 m/yr | 3 |
| Phosphorus | ↑ Improving | -1.5 µg/L/yr | 3 |
Graded lakes near Loon Lake
Loon Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Iosco County
Frequently asked questions about Loon Lake
Where is Loon Lake?
- Loon Lake is a lake in Iosco County, Michigan. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Loon Lake?
- Loon Lake in Iosco County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 23 ft visibility. Maximum depth: 128 ft. Surface area: 416.6 acres.
Is Loon Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Loon Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Loon Lake?
- Loon Lake has a maximum depth of 128 feet. The lake covers 416.6 acres.
What fish are in Loon Lake?
- Fish species found in Loon Lake include Lake herring. Loon Lake is located in Iosco County, Michigan.
Are there boat ramps on Loon Lake?
- Loon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Long Lake. Public access is listed as yes.
Explore Loon Lake across LakeQuality
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Where this data comes from
29 measurements from 1 monitoring station, 2016–2018. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS29 samples · 2016–2018
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)
Named boat-access points from the USGS National Boat Ramps inventory