What is the water quality grade for Eldred Sherwood Lake?

Eldred Sherwood Lake in Hancock County, Wisconsin received a water quality grade of F (Very Poor). Water clarity: 3 ft visibility. Chlorophyll-a (algae): 33.4 µg/L. Surface area: 23 acres.

Is Eldred Sherwood Lake safe to swim in?

Avoid swimming, very poor water quality, potential algae toxins. Eldred Sherwood Lake has an overall water quality grade of F. Algae concentration (chlorophyll-a) is 33.4 µg/L. Always check local health department advisories before swimming.

Eldred Sherwood Lake

Hancock County, WisconsinEutrophic

Eldred Sherwood Lake is a 23-acre productive, nutrient-rich eutrophic lake in Hancock County, IA. Water quality is graded F based on 2 sampling years through 2024. Compared to the 1 other monitored lakes in Hancock County, Eldred Sherwood Lake ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-10-28. Grade methodology: LakeGrade methodology.

Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 3 ft of visibility. Chlorophyll-a: 33.4 µg/L. Trophic State Index: 63.

Metric	Value	Grade
Water Clarity (Secchi Depth)	3 ft	F
Phosphorus	No data
Chlorophyll-a (Algae)	33.4 µg/L	F
Trophic State Index (TSI)	63	Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

Characteristic	Value
Surface Area	23 acres

Location

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County Ranking

Ranked #2 of 2 lakes in Hancock County

Cleaner Lakes Within 30 Miles

Eldred Sherwood Lake holds Grade F. 4 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Hancock County

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Other Grade F Lakes in Wisconsin

Big Creek Lake

Polk County · Clarity: 2.6 ft

Arrowhead Lake

Pottawattamie County · Clarity: 1.8 ft

White Oak Lake

Mahaska County · Clarity: 1.4 ft

Hannen Lake

Benton County · Clarity: 1.2 ft

Briggs Woods Lake

Hamilton County · Clarity: 1.5 ft

Grays Lake

Polk County · Clarity: 1.6 ft

Eutrophic Lakes in Wisconsin

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Reservoir Info (USACE NID)

Eldred Sherwood Lake is a man-made reservoir impounded by the Eldred Sherwood Park Lake Dam (completed 1967), built primarily for other on the TR-EAST BRANCH IOWA RIVER; earth-type dam, 33 ft tall and 555 ft long.

Surface area: 23 ac
Normal storage: 220 ac-ft
Max storage: 360 ac-ft
Drainage area: 4.45 sq mi
Hazard class: Low
Owner: Hancock County Conservation Board

Source: USACE National Inventory of Dams, NID ID IA00438 · Operator website · Matched by proximity (0.05 km)

EPA Impairment Status

Eldred Sherwood Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Pathogens (E. coli, fecal)

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit IA 02-IOW-773 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-10-28

Monitoring stations: 1