Nelson Lake
Nelson Lake in Sawyer County, Wisconsin has a water quality grade of B (Good). Water clarity: 5 ft visibility. Phosphorus: 22.8 µg/L. Surface area: 2503 acres.
- Clarity
- 5 ft
- Max depth
- ~76 ft est.
- Area
- 2,503 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Nelson Lake is a 2,503-acre productive, nutrient-rich eutrophic lake in Sawyer County, Wisconsin with an estimated average depth of about 76 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 5 public boat landings. Compared to the 44 other monitored lakes in Sawyer County, Nelson Lake ranks #18 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-15. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLow algae
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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Murky, only visible to about 5 ft. Phosphorus level: 22.8 µg/L. Trophic State Index: 52.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | 22.8 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Nelson Lake
Compare lakeside cabins, hotels, and vacation rentals near Nelson Lake in Sawyer County, Wisconsin — 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 Wisconsin lake trips
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Nelson Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (432,514 cells/mL) on July 18, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Nelson Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2023Nelson Lake spring shocking and netting survey, 2023Spring Shocking Survey · WI DNR · 2023 (PDF)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~76 ft est. |
| Average Depth | ~15 ft est. |
| Surface Area | 2,503 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wisconsin has not published bathymetry for Nelson 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
- Nelson LakePublic
- GerlachsPublic
- Nelson LakePublic
- Totagatic RiverPublic
- Nelson Lake ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Nelson Lake
- Phipps Landing4.0 km
- Phipps4.2 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Nelson Lake
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.236 m/yr | 6 |
Reservoir Info (USACE NID)
Nelson Lake is a man-made reservoir impounded by the Totagatic (completed 1936), built primarily for recreation on the TOTAGATIC; gravity-type dam, 20 ft tall and 556 ft long.
- Surface area
- 2,503 ac
- Normal storage
- 21,000 ac-ft
- Max storage
- 38,000 ac-ft
- Drainage area
- 49.8 sq mi
- Hazard class
- Low
- Owner
- Sawyer County
Source: USACE National Inventory of Dams, NID ID WI00197 · Operator website
EPA Impairment Status
Nelson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10006780 · Official waterbody report
County Ranking
Ranked #18 of 45 lakes in Sawyer County
Nearby Lakes With Higher Grades
Nelson Lake holds Grade B. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Sawyer County
Frequently asked questions about Nelson Lake
Where is Nelson Lake?
- Nelson Lake is a lake in Sawyer County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Nelson Lake?
- Nelson Lake in Sawyer County, Wisconsin has a water quality grade of B (Good). Water clarity: 5 ft visibility. Phosphorus: 22.8 µg/L. Surface area: 2503 acres.
Is Nelson Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Nelson Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
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 76 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 2503 acres.
Does Nelson Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Nelson Lake (clouds, ice, or an off-season gap). The most recent reading was high (432,514 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Nelson Lake?
- Nelson Lake has 5 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Nelson Lake, Gerlachs, Nelson Lake, Totagatic River, among others. Public access is listed as yes.
Are there campgrounds on Nelson Lake?
- Nelson Lake has 2 public campgrounds from USGS The National Map within 5 km, including Phipps Landing, Phipps. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Nelson Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Sawyer County
Species activity outlook by water temperature and season
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Where to stay at Wisconsin's top lakes, each with its grade
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Where this data comes from
186 measurements from 3 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX186 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (3)
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
Public campgrounds from USGS The National Map Structures, within about 3 miles