Cup Lake
Cup Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.1 ft visibility.
- Clarity
- 5.1 ft
- Public access
- Yes
Next lake in Big Stone County
Why Cup Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: 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 Cup 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 MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Cup Lake is a lake in Big Stone County, Minnesota. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-08-22. Grade methodology: LakeGrade methodology.
Watch Cup Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Cup Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 5.1 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.1 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 Cup Lake
Compare lakeside cabins, hotels, and vacation rentals near Cup Lake in Big Stone County, Minnesota — 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 Cup Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Recreation & Access
- Botker's SloughPublic
Fishing Cup Lake
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Cup Lake under Clean Water Act (NPDES) discharge permits.
- ClintonClinton · 2 mi away · NPDES MN0023078
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.
Graded lakes near Cup Lake
Cup Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Big Stone County
Frequently asked questions about Cup Lake
What is the water quality grade for Cup Lake?
- Cup Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.1 ft visibility.
Is Cup Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Cup Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Are there boat ramps on Cup Lake?
- Cup Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Botker's Slough. Public access is listed as yes.
Explore Cup Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Big Stone County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Minnesota River Watershed, ranked by water quality
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Cup Lake
Other Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
2 measurements from 2 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Department of Agriculture - Pesticide Monitoring
MNDA_PESTICIDE1 sample · 2022 - Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA1 sample · 2022
Analytical methods
- Field measurement/observation, generic method
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