Big Stone Lake
Roberts County, South DakotaView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #2 of 4 in the county
- Public access
- Limited data
Big Stone Lake in Roberts County, South Dakota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 108.5 µg/L. Chlorophyll-a (algae): 70.4 µg/L.
- Clarity
- 3 ft
- Type
- Hypereutrophic
- Public access
- Yes
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Stays near Big Stone Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Stone Lake in Roberts County, South Dakota — 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 Big Stone Lake are listed below.
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Big Stone Lake is a highly nutrient-loaded hypereutrophic lake in Roberts County, South Dakota. Water quality is graded F based on 2 sampling years through 2023. Limited fish-species data available. Public access is available with 7 public boat landings. Compared to the 3 other monitored lakes in Roberts County, Big Stone Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, SD DANR, last sampled 2023-08-09. Grade methodology: LakeQuality methodology.
What Big Stone Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch7 documented ramps
Swimming Safety
Grade onlyLimited data
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.
The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 3 ft of visibility. Phosphorus 108.5 µg/L. Chlorophyll-a 70.4 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 108.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 70.4 µg/L | Poor |
| Trophic State Index (TSI) | 68 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Recreation & Access
- Rearing Ponds Land Use AreaPublic
- Kolb Public Water AccessPublic
- Big Stone Lake #8, OrtonvillePublic
- Ortonville (North)Public
- Kanne (Highway 34)Public
- State Park RoadPublic
Showing 6 of 7 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Big Stone Lake
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Big Stone Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Lg Everist IncOrtonville · 3.1 mi away · NPDES MN0068764Recent violation
- Big Stone CityBig Stone City · 3.8 mi away · NPDES SD0023663
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 #2 of 4 lakes in Roberts County
Nearby Lakes in Roberts County
Frequently asked questions about Big Stone Lake
Where is Big Stone Lake?
- Big Stone Lake is a lake in Roberts County, South Dakota. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Big Stone Lake?
- Big Stone Lake in Roberts County, South Dakota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 108.5 µg/L. Chlorophyll-a (algae): 70.4 µg/L.
Is Big Stone Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Big Stone Lake?
- Big Stone Lake has 7 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Rearing Ponds Land Use Area, Kolb Public Water Access, Big Stone Lake #8, Ortonville, Ortonville (North), among others. Public access is listed as yes.
Explore Big Stone Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at South Dakota's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
South Dakota's cleanest and most-polluted lakes, ranked
More South Dakota Lake Rankings
Where this data comes from
39 measurements from 2 monitoring stations, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA39 samples · 2020–2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory