Sealion Lake
Sealion Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 25.6 ft visibility.
- Clarity
- 25.6 ft
- Trend
- ↓ Declining
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Why Sealion 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 Sealion 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.
Sealion 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.
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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 Sealion Lake
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 25.6 ft down. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 25.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Sealion Lake
Compare lakeside cabins, hotels, and vacation rentals near Sealion 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 Sealion Lake
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Fishing Sealion Lake
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.661 m/yr | 7 |
| Phosphorus | ↓ Declining | +3 µg/L/yr | 3 |
Graded lakes near Sealion Lake
Sealion Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Florence County
Frequently asked questions about Sealion Lake
Where is Sealion Lake?
- Sealion 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 Sealion Lake?
- Sealion Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 25.6 ft visibility.
Is Sealion Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Sealion Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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Where this data comes from
1 measurement 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_WQX1 sample · 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.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)