Lake Redstone
Lake Redstone in Sauk County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 89 µg/L. Surface area: 612 acres.
- Clarity
- 2 ft
- Mean depth
- ~32 ft est.
- Area
- 612 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Lake Redstone →
Next lake in Sauk County
Lake Redstone is a 612-acre productive, nutrient-rich eutrophic lake in Sauk County, Wisconsin with an estimated average depth of about 32 feet. Water quality is graded D based on 1 sampling years through 2026. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 4 public boat landings. Compared to the 6 other monitored lakes in Sauk County, Lake Redstone ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyElevated nutrients
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2 ft of visibility. Phosphorus level: 89 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 89 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Redstone
Compare lakeside cabins, hotels, and vacation rentals near Lake Redstone 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 grade measures nutrients and algae, not lodging — cabins and rentals around Lake Redstone are listed below.
Top-rated places to stay near Lake Redstone
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Planning a trip? Cabins and lodging at Lake Redstone → · more Wisconsin lake trips
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~32 ft est. |
| Surface Area | 612 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Wisconsin has not published bathymetry for Lake Redstone.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Redstone Fox CourtPublic
- Lavalle RoadPublic
- La Valle Mill PondPublic
- Section 11 RoadPublic
Fishing Lake Redstone
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.114 m/yr | 6 |
| Phosphorus | ↓ Declining | +7.12 µg/L/yr | 7 |
Reservoir Info (USACE NID)
Lake Redstone is a man-made reservoir impounded by the Lake Redstone (completed 1967), built primarily for recreation on the Big Creek; gravity-type dam, 50 ft tall and 600 ft long.
- Surface area
- 612 ac
- Normal storage
- 8,700 ac-ft
- Max storage
- 15,200 ac-ft
- Drainage area
- 29.9 sq mi
- Hazard class
- High
- Owner
- Sauk County
Source: USACE National Inventory of Dams, NID ID WI00707 · Operator website
EPA Impairment Status
Lake Redstone is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit WI10002733 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Lake Redstone under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- La Valle Wastewater Treatment FacilityLa Valle · 2.7 mi away · NPDES WI0028878Recent violation
- Kinnamon Ridge Dairy LlcIronton, Town Of · 4.9 mi away · NPDES WI0065129
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.
County Ranking
Ranked #5 of 7 lakes in Sauk County
Nearby Lakes With Higher Grades
Lake Redstone holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Sauk County
Frequently asked questions about Lake Redstone
What is the water quality grade for Lake Redstone?
- Lake Redstone in Sauk County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 89 µg/L. Surface area: 612 acres.
Is Lake Redstone safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Lake Redstone has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
How deep is Lake Redstone?
- No published bathymetric survey covers Lake Redstone, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 32 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 612 acres.
Are there boat ramps on Lake Redstone?
- Lake Redstone has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Redstone Fox Court, Lavalle Road, La Valle Mill Pond, Section 11 Road. Public access is listed as yes.
Explore Lake Redstone across LakeGrade
Depth, room, public access, and the state wake-sport rules
7.4 mi away · cable-pulled, no boat wake
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Where this data comes from
306 measurements from 6 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX306 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (6)
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory