South Twin Lake
Polk County, Wisconsin72 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for South Twin Lake. Here is what has been measured.
- Curly-Leaf Pondweed
- 9 ft max depth
- Public access
- Limited data
South Twin Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 11.7 µg/L. Maximum depth: 9 ft. Surface area: 72 acres.
South Twin Lake is a 72-acre lake in Polk County, Wisconsin with a maximum depth of 9 feet. Water clarity is declining over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-27. Methodology: how these readings are compared.
What South Twin Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing3 species recorded
Swimming conditions
No readingLimited data
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.
No clarity data. Phosphorus 11.7 µg/L. TSI 40.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 11.7µg/L | Measured, not scored 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. | 40 | 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.
Lake Details
Max depth
9 ft
Surface area
72 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.2 mi
HydroLAKES / HydroSHEDS
Elevation
1,047 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
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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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
Worsening5 years
Phosphorus
Improving-15.92 µg/L/yr4 years
Reservoir Info (USACE NID)
South Twin Lake is a man-made reservoir impounded by the Amery (completed 1888), built primarily for recreation on the Apple River; gravity-type dam, 13 ft tall and 190 ft long.
- Surface area
- 639 ac
- Normal storage
- 3,500 ac-ft
- Max storage
- 4,800 ac-ft
- Drainage area
- 134 sq mi
- Hazard class
- High
- Owner
- City Of Amery
Source: USACE National Inventory of Dams, NID ID WI00172 · Operator website · Matched by proximity (0.85 km)
Nearby Lakes in Polk County
Frequently asked questions about South Twin Lake
Where is South Twin Lake?
- South Twin Lake is a lake in Polk 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 Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 11.7 µg/L. Maximum depth: 9 ft. Surface area: 72 acres.
Is South Twin Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is South Twin Lake?
- South Twin Lake has a maximum depth of 9 feet. The lake covers 72 acres.
What fish are in South Twin Lake?
- Fish species found in South Twin Lake include Panfish, Largemouth Bass, Northern Pike. South Twin Lake is located in Polk County, Wisconsin.
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
Depth, room, public access, and the state wake-sport rules
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Where this data comes from
2 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX2 samples · 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
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