Rock Lake
Rock Lake in Vilas County, Wisconsin has a water quality grade of C (Fair). 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 →
- Clarity
- 6.2 ft
- Max depth
- 18 ft
- Area
- 120 acres
- Type
- Eutrophic
- Trend
- → Stable
- Public access
- Yes
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Rock Lake is a 120-acre productive, nutrient-rich eutrophic lake in Vilas County, Wisconsin with a maximum depth of 18 feet. Water quality is graded C based on 1 sampling years through 2026. The lake supports 5 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 1 public boat landing. 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. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 6.2 ft. Phosphorus level: 26 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 ft | Not graded |
| Phosphorus | 26 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay 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
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Wisconsin DNR rates Largemouth Bass as abundant on Rock Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Rock Lake C from EPA Water Quality Portal chemistry, 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
| Characteristic | Value |
|---|---|
| Maximum Depth | 18 ft |
| Surface Area | 120 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- North Turtle LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded 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 data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.058 m/yr | 7 |
| Phosphorus | → Stable | -0.27 µg/L/yr | 7 |
EPA Impairment Status
Rock 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 WI10003782 · Official waterbody report · Matched by proximity (1.85 km)
County Ranking
Ranked #88 of 103 lakes in Vilas County
Nearby Lakes With Higher Grades
Rock Lake holds Grade C. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Vilas County
Frequently asked questions about Rock Lake
Where is Rock Lake?
- Rock Lake is a lake in Vilas County, Wisconsin. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Rock Lake?
- Rock Lake in Vilas County, Wisconsin has a water quality grade of C (Fair). 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?
- Generally safe for swimming, moderate water quality. Rock Lake has a water quality grade of C (Fair). Always check local health department advisories before swimming.
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 a water-quality grade. LakeQuality grades Rock Lake C from EPA Water Quality Portal chemistry, 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.
Are there boat ramps on Rock Lake?
- Rock Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include North Turtle Lake. Public access is listed as yes.
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)
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
Named boat-access points from the USGS National Boat Ramps inventory