Loon Lake
Benzie County, Michigan94 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Oxygen depletion (low DO)
- #17 of 21 in the county
- Limited data
Loon Lake in Benzie County, Michigan has a water quality grade of A (Excellent). Water clarity: 12 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 93.6 acres.
- Clarity
- 12 ft
- Typical in September
- 59°F
- Area
- 94 acres
- Type
- Mesotrophic
- Phosphorus
- 8 µg/L
- Chlorophyll-a
- 2.1 µg/L
- Trend
- ↓ Declining
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Watch Loon Lake’s letter
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Loon Lake is a 94-acre mesotrophic lake in Benzie County, Michigan. Water quality is graded A based on 1 sampling years through 2022. Overall water quality is declining over recent sampling years. The lake supports 13 documented fish species including Black bullhead, Blackchin shiner, and Bluegill. Compared to the 20 other monitored lakes in Benzie County, Loon Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-10. Grade methodology: LakeQuality methodology.
What Loon Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12 ft of visibility
- Fishing13 species recorded
Swimming Safety
Grade onlyLimited data
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. Loon Lake is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Good clarity, visible to about 12 ft. Phosphorus 8 µg/L. Chlorophyll-a 2.1 µg/L. TSI 38. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12 ft | Not graded |
| Phosphorus | 8 µg/L | Not graded |
| Chlorophyll-a (Algae) | 2.1 µg/L | Good |
| Trophic State Index (TSI) | 38 | Mesotrophic |
Moderate nutrients, good water quality
Water Temperature
Loon Lake typically sits around 59°F at the surface in September. Summer average is about 57°F. Usually warmest in Aug (about 59°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 148 field readings (2013–2022) via the EPA Water Quality Portal. See the full Loon Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 94 acres |
No bathymetric survey has been published for Loon Lake, so its depth is not documented here.
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Loon Lake
Water Quality Trend: ↓ Declining
Based on 9 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.604 m/yr | 9 |
| Phosphorus | ↓ Declining | +1.54 µg/L/yr | 9 |
| Chlorophyll-a | ↓ Declining | +0.13 µg/L/yr | 2 |
EPA Impairment Status
Loon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MI040601040206-05 · Official waterbody report · Matched by proximity (0.16 km)
County Ranking
Ranked #17 of 21 lakes in Benzie County
Nearby Lakes in Benzie County
Frequently asked questions about Loon Lake
Where is Loon Lake?
- Loon Lake is a lake in Benzie County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Loon Lake?
- Loon Lake in Benzie County, Michigan has a water quality grade of A (Excellent). Water clarity: 12 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 93.6 acres.
Is Loon Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Loon Lake is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO). Check local advisories before you swim.
What is the water temperature of Loon Lake?
- Loon Lake typically sits around 59°F at the surface in September, from 148 EPA Water Quality Portal field readings (2013–2022). That is a typical value for the month, not a live reading.
What fish are in Loon Lake?
- Fish species found in Loon Lake include Black bullhead, Blackchin shiner, Bluegill, Bluntnose minnow, Central mudminnow, Green sunfish, Lake herring, Largemouth bass, Pumpkinseed, Rock bass, Western banded killifish, White sucker, Yellow perch. Loon Lake is located in Benzie County, Michigan.
Explore Loon Lake across LakeQuality
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Moderate nutrients, good water quality
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Planning a trip around Sleeping Bear Dunes?
Loon Lake is about 16 miles from Sleeping Bear Dunes National Lakeshore. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Sleeping Bear Dunes →More Michigan Lake Rankings
Other Grade A Lakes in Michigan
Mesotrophic Lakes in Michigan
Where this data comes from
16 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS16 samples · 2022
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