Hart Lake
Bayfield County, Wisconsin257 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Hart Lake. Here is what has been measured.
- 54 ft max depth
- Limited data
Hart Lake in Bayfield County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 21.5 ft visibility. Maximum depth: 54 ft. Surface area: 257 acres.
Wisconsin DNR rates Largemouth Bass as abundant on Hart Lake. DNR survey details →
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. Methodology: how these readings are compared.
What Hart Lake is good for
From access and monitoring records, not editorial picks.
- Clear water21.5 ft of visibility
- Fishing6 species recorded
- Deep water54 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Hart 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 Hart Lake
These are the measurements Wisconsin DNR publishes for Hart Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 21.5 ft down. TSI 33.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 21.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| 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. | 33 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Hart Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR rates Largemouth Bass as abundant on Hart Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hart Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. 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 1993. 4 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
54 ft
Surface area
257 acres
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Stays near Hart Lake
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Fish Species
Click a species to see every 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.
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Nearby Lakes in Bayfield County
Frequently asked questions about Hart Lake
Where is Hart Lake?
- Hart Lake is a lake in Bayfield County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Hart Lake?
- Hart Lake in Bayfield County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 21.5 ft visibility. Maximum depth: 54 ft. Surface area: 257 acres.
Is Hart Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
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.
What did the DNR fisheries survey find at Hart Lake?
- Wisconsin DNR rates Largemouth Bass as abundant on Hart Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hart Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
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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)
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
Fish and recreation data from Wisconsin DNR Lakes