Nelson Lake
Oliver County, North Dakota660 acresView mapDirections
ND DEQ publishes the water-quality measurements for Nelson Lake. Here is what has been measured.
- Hypereutrophic
- 33 ft max depth
- Public access
- Limited data
Nelson Lake in Oliver County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 1.3 ft visibility. Phosphorus: 275 µg/L. Chlorophyll-a (algae): 23.1 µg/L. Surface area: 660 acres.
Nelson Lake is a 660-acre highly nutrient-loaded hypereutrophic lake in Oliver County, North Dakota with an estimated average depth of about 33 feet. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Oliver County, Nelson Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-10-16. Methodology: how these readings are compared.
What Nelson Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLimited data
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. Check local advisories before you swim.
Whether Nelson Lake is safe to swim in today is a call for the North Dakota Department of Environmental Quality 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 ND DEQ 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.
Very murky, less than 1.3 ft of visibility. Phosphorus 275 µg/L. Chlorophyll-a 23.1 µg/L. TSI 73.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 275µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 23.1µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 73 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Nelson Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Nelson Lake typically sits around 60°F at the surface in October. Summer average is about 79°F. Usually warmest in Jul (about 82°F) and coldest in Oct (about 60°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (60°F) to its warmest (82°F).
Typical surface water temperature by month, from 14 field readings (2023–2023) via the EPA Water Quality Portal. See the full Nelson Lake water temperature breakdown →
Lake Details
Max depth
~33 ft est.
Surface area
660 acres
Public access
Yes
Listed by ND DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Dakota has not published bathymetry for Nelson Lake.
Lake Size & Watershed
Watershed (drainage) area
146 sq mi
HydroLAKES / HydroSHEDS
Shoreline
6.8 mi
HydroLAKES / HydroSHEDS
Elevation
1,919 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.
Recreation & Access
- Nelson LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Nelson Lake
Compare lakeside cabins, hotels, and vacation rentals near Nelson Lake in Oliver County, North 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.
Top-rated places to stay near Nelson Lake
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Planning a trip? Cabins and lodging at Nelson Lake → · more North Dakota lake trips
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Fishing Nelson Lake
Reservoir Info (USACE NID)
Nelson Lake is a man-made reservoir impounded by the Nelson Lake Dam (completed 1967), built primarily for other on the Square Butte Creek; earth-type dam, 66 ft tall and 2,200 ft long.
- Surface area
- 660 ac
- Normal storage
- 10,350 ac-ft
- Max storage
- 20,122 ac-ft
- Drainage area
- 146 sq mi
- Hazard class
- High
- Owner
- Minnkota Power Coop
All listed purposes: Other;Recreation.
Source: USACE National Inventory of Dams, NID ID ND00096 · Operator website
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Nelson Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 4 facilities have a reported Clean Water Act violation in the past three years.
- Minnkota Power CooperativeCenter · 0.2 mi away · NPDES ND0000370MajorRecent violation
- Minnesota PowerCenter · 0.7 mi away · NPDES ND0026361Recent violation
- Bni Coal Ltd CenterCenter · 1.2 mi away · NPDES ND0024601Recent violation
- Center Coal CoCenter · 1.4 mi away · NPDES ND0025321Recent violation
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.
Nearby Lakes in Oliver County
Frequently asked questions about Nelson Lake
Where is Nelson Lake?
- Nelson Lake is a lake in Oliver County, North Dakota. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Nelson Lake?
- Nelson Lake in Oliver County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 1.3 ft visibility. Phosphorus: 275 µg/L. Chlorophyll-a (algae): 23.1 µg/L. Surface area: 660 acres.
Is Nelson Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Nelson Lake?
- Nelson Lake typically sits around 60°F at the surface in October, from 14 EPA Water Quality Portal field readings (2023–2023). 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 33 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 660 acres.
Are there boat ramps on Nelson Lake?
- Nelson Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Nelson Lake. Public access is listed as yes.
Can I fish at Nelson Lake?
- Nelson Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by North Dakota's fish and wildlife agency, so check its current regulations before you go.
Explore Nelson Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its readings
North Dakota's cleanest lakes, ranked on agency measurements
More lakes in North Dakota
Other Lakes in North Dakota
Hypereutrophic Lakes in North Dakota
Where this data comes from
21 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX21 samples · 2023
Analytical methods
- Phosphorus by Colorimetry
- 447.0 ~ EPA; Chlorophyll a and b in phytoplankton by HPLC/UV
- 4500 NO3 E ~ Nitrate in Water- Cadmium Reduction
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Depth, fish, and access data from North Dakota Game & Fish
Named boat-access points from the USGS National Boat Ramps inventory