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F

Radigan Flowage Lake

Douglas County, WisconsinEutrophic

On the LakeGrade rubric Radigan Flowage Lake fails the cutoffs — a TSI of 68 and persistent algal pressure put it in the bottom tier. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. At 150 acres, Radigan Flowage Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within the 44 graded lakes of Douglas County, Radigan Flowage Lake sits at rank 44, near the bottom of the county list.

No invasive species are currently listed at Radigan Flowage Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Radigan Flowage Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-09. Grade methodology: LakeGrade methodology.

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Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 2 ft of visibility. Phosphorus level: 94.9 µg/L. Trophic State Index: 68.

MetricValueGrade
Water Clarity (Secchi Depth)2 ftF
Phosphorus94.9 µg/LF
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)68Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Surface Area150 acres
Public AccessYes

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #44 of 44 lakes in Douglas County

Cleaner Lakes Within 30 Miles

Radigan Flowage Lake holds Grade F. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Douglas County

State Parks Near Radigan Flowage Lake

Reservoir Info (USACE NID)

Radigan Flowage Lake is a man-made reservoir impounded by the Radigan (completed 1938), built primarily for recreation on the Upper Tamarack River; gravity-type dam, 12 ft tall and 300 ft long.

Surface area
150 ac
Normal storage
230 ac-ft
Max storage
420 ac-ft
Drainage area
41 sq mi
Hazard class
High
Owner
Town Of Dairyland

Source: USACE National Inventory of Dams, NID ID WI00257 · Operator website

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Public boat-access points from the USGS National Boat Ramps inventory

Most recent sample: 2025-09-09

Monitoring stations: 1

Where to stay near Radigan Flowage Lake

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