South Twin Lake
Washburn County, Wisconsin106 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for South Twin Lake. Here is what has been measured.
- Oligotrophic
- 29 ft max depth
- Public access
South Twin Lake in Washburn County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 14 ft visibility. Phosphorus: 11.5 µg/L. Maximum depth: 29 ft. Surface area: 106 acres.
Wisconsin DNR rates Panfish as abundant on South Twin Lake. DNR survey details →
South Twin Lake is a 106-acre cold, clear oligotrophic lake in Washburn County, Wisconsin with a maximum depth of 29 feet. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 26 other monitored lakes in Washburn County, South Twin Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-17. Methodology: how these readings are compared.
What South Twin Lake is good for
From access and monitoring records, not editorial picks.
- Clear water14 ft of visibility
- Boat launch1 documented ramp
- Fishing4 species recorded
Swimming conditions
Readings onlyLow 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 South Twin 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 South Twin Lake
These are the measurements Wisconsin DNR publishes for South Twin Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 14 ft. Phosphorus 11.5 µg/L. TSI 39.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 14ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 11.5µg/L | Good 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. | 39 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about South Twin Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
South Twin Lake typically sits around 73°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 79°F) and coldest in Aug (about 73°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (73°F) to its warmest (79°F).
Typical surface water temperature by month, from 12 field readings (2024–2025) via the EPA Water Quality Portal. See the full South Twin Lake water temperature breakdown →
Wisconsin DNR rates Panfish as abundant on South Twin Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows South Twin Lake’s water-quality measurements separately, and the water-quality trend over 6 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 1994. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
29 ft
Surface area
106 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- South Twin LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near South Twin Lake
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Top-rated places to stay near South Twin Lake
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Follow South Twin Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing South Twin 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 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Stable-0.07 µg/L/yr6 years
Nearby Lakes in Washburn County
Frequently asked questions about South Twin Lake
Where is South Twin Lake?
- South Twin Lake is a lake in Washburn County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of South Twin Lake?
- South Twin Lake in Washburn County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 14 ft visibility. Phosphorus: 11.5 µg/L. Maximum depth: 29 ft. Surface area: 106 acres.
Is South Twin Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of South Twin Lake?
- South Twin Lake typically sits around 73°F at the surface in August, from 12 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is South Twin Lake?
- South Twin Lake has a maximum depth of 29 feet. The lake covers 106 acres.
What fish are in South Twin Lake?
- Fish species found in South Twin Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. South Twin Lake is located in Washburn County, Wisconsin.
What did the DNR fisheries survey find at South Twin Lake?
- Wisconsin DNR rates Panfish as abundant on South Twin Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows South Twin Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on South Twin Lake?
- South Twin Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include South Twin Lake. Public access is listed as yes.
Can I fish at South Twin Lake?
- South Twin Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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 South Twin Lake across LakeQuality
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Where this data comes from
31 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_WQX31 samples · 2020–2025
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
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory