What is the water quality grade for Nelson Lake?

Nelson Lake in Crawford County, Wisconsin received a water quality grade of D (Poor). Water clarity: 3.8 ft visibility. Chlorophyll-a (algae): 30.6 µg/L. Surface area: 11 acres.

Is Nelson Lake safe to swim in?

Swimming not recommended, poor water quality with high algae risk. Nelson Lake has an overall water quality grade of D. Algae concentration (chlorophyll-a) is 30.6 µg/L. Always check local health department advisories before swimming.

Nelson Lake

Crawford County, WisconsinEutrophic

Nelson Lake is a 11-acre productive, nutrient-rich eutrophic lake in Crawford County, IA. Water quality is graded D based on 2 sampling years through 2024. Compared to the 1 other monitored lakes in Crawford County, Nelson Lake ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-03. 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 3.8 ft. Chlorophyll-a: 30.6 µg/L. Trophic State Index: 61.

Metric	Value	Grade
Water Clarity (Secchi Depth)	3.8 ft	D
Phosphorus	No data
Chlorophyll-a (Algae)	30.6 µg/L	F
Trophic State Index (TSI)	61	Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

Characteristic	Value
Surface Area	11 acres

Location

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County Ranking

Ranked #1 of 2 lakes in Crawford County

Cleaner Lakes Within 30 Miles

Nelson Lake holds Grade D. 3 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Crawford County

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Other Grade D Lakes in Wisconsin

Storm Lake Max Depth

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Nodaway Lake

Adair County · Clarity: 2.8 ft

Loch Ayr Lake

Ringgold County · Clarity: 2 ft

Lake Minnewashta

Dickinson County · Clarity: 2.8 ft

Clear Lake

Cerro Gordo County · Clarity: 2.1 ft

Eutrophic Lakes in Wisconsin

Big Creek Lake Storm Lake Max Depth Lost Island Lake Nodaway Lake

Reservoir Info (USACE NID)

Nelson Lake is a man-made reservoir impounded by the Iowa Noname8 (completed 1964), built primarily for recreation on the TR-BOYER RIVER; earth-type dam, 38 ft tall and 522 ft long.

Surface area: 11 ac
Normal storage: 111 ac-ft
Max storage: 220 ac-ft
Drainage area: 0.97 sq mi
Hazard class: Low
Owner: Crawford County Conservation Board

Source: USACE National Inventory of Dams, NID ID IA00233 · Operator website · Matched by proximity (0.08 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-09-03

Monitoring stations: 1