Rock Lake
Vilas County, Wisconsin120 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Rock Lake. Here is what has been measured.
- Eutrophic
- Rusty Crayfish
- 18 ft max depth
- Public access
Rock Lake in Vilas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 6.2 ft visibility. Phosphorus: 26 µg/L. Maximum depth: 18 ft. Surface area: 120 acres.
Wisconsin DNR rates Largemouth Bass as abundant on Rock Lake. DNR survey details →
Rock Lake is a 120-acre productive, nutrient-rich eutrophic lake in Vilas County, Wisconsin with a maximum depth of 18 feet. The lake supports 5 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available. Compared to the 102 other monitored lakes in Vilas County, Rock Lake ranks #88 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-07-09. Methodology: how these readings are compared.
Rock Lake covers about 120 acres in Vilas County. If you are planning to stay, you can search lake houses and cabins around Rock Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Rock Lake is good for
From access and monitoring records, not editorial picks.
- Fishing5 species recorded
Swimming conditions
Readings onlyModerate algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Rock Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Rock Lake
These are the measurements Wisconsin DNR publishes for Rock Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 6.2 ft. Phosphorus 26 µg/L. TSI 51.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 6.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 26µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 51 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Rock Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR rates Largemouth Bass as abundant on Rock Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rock Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is stable. 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. Monitored by volunteers since 1991. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
18 ft
Surface area
120 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
19 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.5 mi
HydroLAKES / HydroSHEDS
Elevation
1,621 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Rock Lake
Compare lakeside cabins, hotels, and vacation rentals near Rock 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 Rock Lake
Prices for Oct 16–18, 4 adults. Change dates on the map below.
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Fish Species
Click a species to see every lake where it is documented.
Fishing Rock Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Stable
Based on 7 years of monitoring (2020–2026).
Water clarity
Stable7 years
Phosphorus
Stable-0.27 µg/L/yr7 years
Nearby Lakes in Vilas County
Frequently asked questions about Rock Lake
Where is Rock Lake?
- Rock Lake is a lake in Vilas County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Rock Lake?
- Rock Lake in Vilas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 6.2 ft visibility. Phosphorus: 26 µg/L. Maximum depth: 18 ft. Surface area: 120 acres.
Is Rock Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Rock Lake?
- Rock Lake has a maximum depth of 18 feet. The lake covers 120 acres.
What fish are in Rock Lake?
- Fish species found in Rock Lake include Musky, Panfish, Largemouth Bass, Northern Pike, Walleye. Rock Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Rock Lake?
- Wisconsin DNR rates Largemouth Bass as abundant on Rock Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rock Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Rock Lake?
- Public access to Rock Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Rock Lake across LakeQuality
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Where this data comes from
72 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX72 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes