South Twin Lake
South Twin Lake in Portage County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 9 ft. Surface area: 54 acres.
Wisconsin DNR lists Panfish as present on South Twin Lake. DNR survey details →
- Clarity
- 5 ft
- Max depth
- 9 ft
- Area
- 54 acres
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Why South Twin Lake has no grade
We grade a lake only when the monitoring record supports a letter: 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 South Twin Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). 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.
South Twin Lake is a 54-acre lake in Portage County, Wisconsin with a maximum depth of 9 feet. The lake supports 1 documented fish species including Panfish.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2021-09-22. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for South Twin Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 5 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near South Twin Lake
Compare lakeside cabins, hotels, and vacation rentals near South Twin Lake in Portage 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 South Twin Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Wisconsin DNR lists Panfish as present on South Twin Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on South Twin Lake — official chemistry is on file, not a letter. 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. 1 station on file (most recent sample 2021).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 9 ft |
| Surface Area | 54 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 South Twin Lake
Graded lakes near South Twin Lake
South Twin Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Portage County
Frequently asked questions about South Twin Lake
Where is South Twin Lake?
- South Twin Lake is a lake in Portage County, Wisconsin. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for South Twin Lake?
- South Twin Lake in Portage County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 9 ft. Surface area: 54 acres.
Is South Twin Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. South Twin 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 South Twin Lake?
- South Twin Lake has a maximum depth of 9 feet. The lake covers 54 acres.
What fish are in South Twin Lake?
- Fish species found in South Twin Lake include Panfish. South Twin Lake is located in Portage County, Wisconsin.
What did the DNR fisheries survey find at South Twin Lake?
- Wisconsin DNR lists Panfish as present on South Twin Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on South Twin Lake — official chemistry is on file, not a letter. Catch rate is not a swim clearance and is not a weekly bite report.
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Where this data comes from
1 measurement from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX1 sample · 2021
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