Hill Slough Lake
Sauk County, WisconsinView mapDirections
Wisconsin DNR publishes the water-quality measurements for Hill Slough Lake. Here is what has been measured.
- Eutrophic
- Limited data
Hill Slough Lake in Sauk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 4.4 ft visibility. Phosphorus: 42.7 µg/L.
Hill Slough Lake is a productive, nutrient-rich eutrophic lake in Sauk County, Wisconsin. Compared to the 6 other monitored lakes in Sauk County, Hill Slough Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-10-29. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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 Hill Slough 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 Hill Slough Lake
These are the measurements Wisconsin DNR publishes for Hill Slough Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.4 ft. Phosphorus 42.7 µg/L. TSI 57.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 42.7µg/L | Poor 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. | 57 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Hill Slough Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Hill Slough Lake typically sits around 49°F at the surface in October. Summer average is about 67°F. Usually warmest in Jun (about 77°F) and coldest in Oct (about 49°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (49°F) to its warmest (77°F).
Typical surface water temperature by month, from 19 field readings (2025–2025) via the EPA Water Quality Portal. See the full Hill Slough Lake water temperature breakdown →
Stays via Stay22
Stays near Hill Slough Lake
Compare lakeside cabins, hotels, and vacation rentals near Hill Slough Lake in Sauk 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Hill Slough Lake are listed below.
Top-rated places to stay near Hill Slough Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fishing Hill Slough Lake
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Hill Slough Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Spring Green Golf Club Sanitary Dist #2 WwtfWyoming · 1.3 mi away · NPDES WI0028363Recent violation
- Spring Green Wastewater Treatment FacilitySpring Green · 1.6 mi away · NPDES WI0060801Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Sauk County
Frequently asked questions about Hill Slough Lake
Where is Hill Slough Lake?
- Hill Slough Lake is a lake in Sauk County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Hill Slough Lake?
- Hill Slough Lake in Sauk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 4.4 ft visibility. Phosphorus: 42.7 µg/L.
Is Hill Slough 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 Hill Slough Lake?
- Hill Slough Lake typically sits around 49°F at the surface in October, from 19 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
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Where this data comes from
14 measurements from 2 monitoring stations, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX14 samples · 2025
Analytical methods
- Phosphorus by Colorimetry
- Turbidity in Water
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)