Prong Lake
Prong Lake in Vilas County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 13.5 ft visibility. Maximum depth: 50 ft. Surface area: 31 acres.
Wisconsin DNR rates Panfish as abundant on Prong Lake. DNR survey details →
- Clarity
- 13.5 ft
- Max depth
- 50 ft
- Area
- 31 acres
- Trend
- ↑ Improving
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Why Prong 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 Prong 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.
Prong Lake is a 31-acre lake in Vilas County, Wisconsin with a maximum depth of 50 feet. Overall water quality is improving over recent sampling years. The lake supports 2 documented fish species including Panfish and Largemouth Bass.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-09-15. Grade methodology: LakeQuality methodology.
Watch Prong Lake water quality
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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 Prong Lake
These readings exist but are not enough for an A–F grade — see why.
Good clarity, visible to about 13.5 ft. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Prong Lake
Compare lakeside cabins, hotels, and vacation rentals near Prong Lake in Vilas 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 Prong Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Wisconsin DNR rates Panfish as abundant on Prong Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Prong Lake — official chemistry is on file, not a letter, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2024).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 50 ft |
| Surface Area | 31 acres |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Prong Lake
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.325 m/yr | 4 |
| Phosphorus | ↑ Improving | -4.03 µg/L/yr | 7 |
EPA Impairment Status
Prong 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 WI10007641 · Official waterbody report · Matched by proximity (2.34 km)
Graded lakes near Prong Lake
Prong Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Vilas County
Frequently asked questions about Prong Lake
Where is Prong Lake?
- Prong Lake is a lake in Vilas 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 Prong Lake?
- Prong Lake in Vilas County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 13.5 ft visibility. Maximum depth: 50 ft. Surface area: 31 acres.
Is Prong Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Prong 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 Prong Lake?
- Prong Lake has a maximum depth of 50 feet. The lake covers 31 acres.
What fish are in Prong Lake?
- Fish species found in Prong Lake include Panfish, Largemouth Bass. Prong Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Prong Lake?
- Wisconsin DNR rates Panfish as abundant on Prong Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Prong Lake — official chemistry is on file, not a letter, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
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Where this data comes from
1 measurement from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX1 sample · 2024
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes