Long Lake
Long Lake in Cottonwood County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility.
- Clarity
- 1 ft
- Mean depth
- ~10 ft est.
- Trend
- → Stable
- Public access
- Yes
Next lake in Cottonwood County
Why Long 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 Long Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. 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.
Long Lake is a lake in Cottonwood County, Minnesota with an estimated average depth of about 10 feet. 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 2022-05-05. Grade methodology: LakeGrade methodology.
Watch Long 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 Long Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 1 ft of visibility. Trophic State Index: 77.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Cottonwood 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 Long 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 →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~10 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Long Lake.
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
- Eagle LakePublic
Fishing Long Lake
Water Quality Trend: → Stable
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | 0 m/yr | 2 |
EPA Impairment Status
Long Lake 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 MN17-0020-00 · Official waterbody report · Matched by proximity (1.57 km)
Graded lakes near Long Lake
Long Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Cottonwood County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Cottonwood County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility.
Is Long Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Long 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 Long Lake?
- No published bathymetric survey covers Long Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 10 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Long Lake?
- Long Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Eagle Lake. Public access is listed as yes.
Explore Long Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Cottonwood County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Long Lake
Other Lakes in Minnesota
Hypereutrophic Lakes in Minnesota
Where this data comes from
18 measurements from 1 monitoring station, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA18 samples · 2020–2022
Analytical methods
- Field measurement/observation, generic method
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory