Rainbow Lake
Rainbow Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 13.1 µg/L. Maximum depth: 36 ft. Surface area: 148 acres.
Wisconsin DNR lists Walleye as common on Rainbow Lake. DNR survey details →
- Clarity
- 6 ft
- Typical in August
- 72°F
- Max depth
- 36 ft
- Area
- 148 acres
- Type
- Mesotrophic
- Trend
- → Stable
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Rainbow Lake is a 148-acre mesotrophic lake in Vilas County, Wisconsin with a maximum depth of 36 feet. Water quality is graded B based on 1 sampling years through 2026. Water clarity is improving over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Compared to the 102 other monitored lakes in Vilas County, Rainbow Lake ranks #20 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-22. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Murky, only visible to about 6 ft. Phosphorus level: 13.1 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | 13.1 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Rainbow Lake
Compare lakeside cabins, hotels, and vacation rentals near Rainbow 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 Rainbow Lake
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Water Temperature
Rainbow Lake typically sits around 72°F at the surface in August. Summer average is about 69°F. Usually warmest in Jul (about 72°F) and coldest in Apr (about 47°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2024–2025) via the EPA Water Quality Portal. See the full Rainbow Lake water temperature breakdown →
Wisconsin DNR lists Walleye as common on Rainbow Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Rainbow Lake B 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 2005. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 36 ft |
| Surface Area | 148 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 Rainbow Lake
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.371 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.38 µg/L/yr | 7 |
EPA Impairment Status
Rainbow 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 (2.97 km)
County Ranking
Ranked #20 of 103 lakes in Vilas County
Nearby Lakes in Vilas County
Frequently asked questions about Rainbow Lake
Where is Rainbow Lake?
- Rainbow Lake is a lake in Vilas County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Rainbow Lake?
- Rainbow Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 13.1 µg/L. Maximum depth: 36 ft. Surface area: 148 acres.
Is Rainbow Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Rainbow Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Rainbow Lake?
- Rainbow Lake typically sits around 72°F at the surface in August, from 10 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Rainbow Lake?
- Rainbow Lake has a maximum depth of 36 feet. The lake covers 148 acres.
What fish are in Rainbow Lake?
- Fish species found in Rainbow Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Rainbow Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Rainbow Lake?
- Wisconsin DNR lists Walleye as common on Rainbow Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Rainbow Lake B 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.
Explore Rainbow Lake across LakeQuality
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Fish species and best lakes in Vilas County
Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
65 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_WQX65 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