Loon Lake
Loon Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 16.8 ft visibility.
- Clarity
- 16.8 ft
- Trend
- ↓ Declining
Next lake in Florence County
Swipe left or right on this bar to open the next or previous lake.
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, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). 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 WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Loon Lake is a lake in Florence County, Wisconsin. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2022-07-08. Grade methodology: LakeQuality methodology.
Watch Loon Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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 16.8 ft down. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.8 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 36 | 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 Florence County, Wisconsin — 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
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 Wisconsin’s top lakes →
Fishing Loon Lake
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.286 m/yr | 7 |
| Phosphorus | ↓ Declining | +3.79 µg/L/yr | 6 |
Graded lakes near Loon Lake
Loon Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Florence County
Frequently asked questions about Loon Lake
Where is Loon Lake?
- Loon Lake is a lake in Florence County, Wisconsin. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Loon Lake?
- Loon Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 16.8 ft visibility.
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.
Explore Loon Lake across LakeQuality
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Florence County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
Other Lakes in Wisconsin
Oligotrophic Lakes in Wisconsin
Where this data comes from
2 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX2 samples · 2022
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.