Nelson Lake
Nelson Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
- Clarity
- 10 ft
- Typical in August
- 75°F
- Type
- Mesotrophic
- Public access
- Yes
Next lake in Otter Tail County
Nelson Lake is a mesotrophic lake in Otter Tail County, Minnesota. Water quality is graded A based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 2 public boat landings. 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. Grade methodology: LakeGrade methodology.
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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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 10 ft. Phosphorus level: 20 µg/L. Chlorophyll-a: 4.9 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | 4.9 µg/L | Good |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Nelson Lake
Compare lakeside cabins, hotels, and vacation rentals near Nelson Lake in Otter Tail 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.
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Water Temperature
Nelson Lake typically sits around 75°F at the surface in August. 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.
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 Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Adley LakePublic
- Fish LakePublic
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN56-0065-00 · Official waterbody report
County Ranking
Ranked #44 of 66 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
Frequently asked questions about Nelson Lake
What is the water quality grade for Nelson Lake?
- Nelson Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
Is Nelson Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Nelson Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Nelson Lake?
- Nelson Lake typically sits around 75°F at the surface in August, 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?
- The available depth estimate for Nelson Lake is shallower than its measured water clarity, which cannot be right, so no depth is shown.
Are there boat ramps on Nelson Lake?
- Nelson Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Adley Lake, Fish Lake. Public access is listed as yes.
Explore Nelson Lake across LakeGrade
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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)
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)
Named boat-access points from the USGS National Boat Ramps inventory