Tolna Dam Lake
Nelson County, WisconsinLimited DataEutrophic
Tolna Dam Lake is a 166-acre productive, nutrient-rich eutrophic lake in Nelson County, ND. Water quality is graded D based on 1 sampling years through 2025. Compared to the 8 other monitored lakes in Nelson County, Tolna Dam Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2025-10-13. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 4.9 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.9 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 166.3 acres |
Location
County Ranking
Ranked #5 of 9 lakes in Nelson County
Cleaner Lakes Within 30 Miles
Tolna Dam Lake holds Grade D. 2 nearby lakes hold higher grades.
- CRed Willow LakeGriggs County · 11.1 mi · Higher grade (D → C)
- CEast Devils LakeRamsey County · 15.5 mi · Higher grade (D → C)
Nearby Lakes in Nelson County
More Wisconsin Lake Rankings
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Tolna Dam Lake is a man-made reservoir impounded by the Tolna Dam 1 (completed 1936), built primarily for recreation on the Tolna Coulee; earth-type dam, 36 ft tall and 520 ft long.
- Surface area
- 166.3 ac
- Normal storage
- 2,027 ac-ft
- Max storage
- 3,080 ac-ft
- Drainage area
- 40 sq mi
- Hazard class
- Significant
- Owner
- Nelson County WRB
Source: USACE National Inventory of Dams, NID ID ND00027 · Operator website · Matched by proximity (0.27 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-13
Monitoring stations: 1