Nelson Lake
Otter Tail County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Nelson Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 35 ft max depth
- Public access
- Limited data
Nelson Lake in Otter Tail County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
Nelson Lake is a mesotrophic lake in Otter Tail County, Minnesota with an estimated average depth of about 35 feet. Limited fish-species data available. Public access is available. Compared to the 65 other monitored lakes in Otter Tail County, Nelson Lake ranks #44 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-09-07. Methodology: how these readings are compared.
What Nelson Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10 ft of visibility
Swimming conditions
Readings onlyRecreation use not supported
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. Nelson Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Nelson Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Nelson Lake
These are the measurements Minnesota PCA publishes for Nelson Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10 ft. Phosphorus 20 µg/L. Chlorophyll-a 4.9 µg/L. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 4.9µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Nelson Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Nelson Lake typically sits around 73°F at the surface in September. Summer average is about 73°F. Usually warmest in Jul (about 76°F) and coldest in Jun (about 67°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (67°F) to its warmest (76°F).
Typical surface water temperature by month, from 23 field readings (2011–2022) via the EPA Water Quality Portal. See the full Nelson Lake water temperature breakdown →
Lake Details
Max depth
~35 ft est.
Public access
Yes
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Nelson Lake.
Lake Size & Watershed
Watershed (drainage) area
9 sq mi
HydroLAKES / HydroSHEDS
Surface area
255 acres
HydroLAKES / HydroSHEDS
Shoreline
2.7 mi
HydroLAKES / HydroSHEDS
Elevation
1,444 ft
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.
Stays via Stay22
Stays near Nelson Lake
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Top-rated places to stay near Nelson Lake
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Fishing Nelson Lake
EPA Impairment Status
Nelson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN56-0065-00 · Official waterbody report
Nearby Lakes in Otter Tail County
Frequently asked questions about Nelson Lake
Where is Nelson Lake?
- Nelson Lake is a lake in Otter Tail County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Nelson Lake?
- Nelson Lake in Otter Tail County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
Is Nelson Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Nelson Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Nelson Lake?
- Nelson Lake typically sits around 73°F at the surface in September, from 23 EPA Water Quality Portal field readings (2011–2022). That is a typical value for the month, not a live reading.
How deep is Nelson Lake?
- No published bathymetric survey covers Nelson Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 35 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Nelson Lake?
- Public access to Nelson Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
13 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA13 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder