Hart Lake
Hart Lake in Bayfield County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 21.5 ft visibility. Maximum depth: 54 ft. Surface area: 257 acres.
- Clarity
- 21.5 ft
- Max depth
- 54 ft
- Area
- 257 acres
- Trend
- ↓ Declining
Next lake in Bayfield County
Why Hart Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: 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 Hart Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. 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.
Hart Lake is a 257-acre lake in Bayfield County, Wisconsin with a maximum depth of 54 feet. Overall water quality is declining over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-10-12. Grade methodology: LakeGrade methodology.
Watch Hart Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Hart Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Crystal clear, you can see 21.5 ft down. Trophic State Index: 33.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 21.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 33 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Hart Lake
Compare lakeside cabins, hotels, and vacation rentals near Hart Lake in Bayfield 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 Hart Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 54 ft |
| Surface Area | 257 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 Hart 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1993. 4 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.433 m/yr | 6 |
Graded lakes near Hart Lake
Hart Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Bayfield County
Frequently asked questions about Hart Lake
What is the water quality grade for Hart Lake?
- Hart Lake in Bayfield County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 21.5 ft visibility. Maximum depth: 54 ft. Surface area: 257 acres.
Is Hart Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Hart 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 Hart Lake?
- Hart Lake has a maximum depth of 54 feet. The lake covers 257 acres.
What fish are in Hart Lake?
- Fish species found in Hart Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Hart Lake is located in Bayfield County, Wisconsin.
Explore Hart Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Bayfield County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Hayward Lakes area
Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
Other Lakes in Wisconsin
Oligotrophic Lakes in Wisconsin
Where this data comes from
26 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX26 samples · 2020–2025
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)
Fish and recreation data from Wisconsin DNR Lakes