Turtle Flambeau Flowage Lake
Turtle Flambeau Flowage Lake in Iron County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 19.4 µg/L. Surface area: 13798 acres.
- Clarity
- 6 ft
- Mean depth
- ~16 ft est.
- Area
- 13,798 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Iron County
Turtle Flambeau Flowage Lake is a 13,798-acre mesotrophic lake in Iron County, Wisconsin with an estimated average depth of about 16 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 15 other monitored lakes in Iron County, Turtle Flambeau Flowage Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-29. Grade methodology: LakeGrade 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 6 ft. Phosphorus level: 19.4 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | 19.4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Turtle Flambeau Flowage Lake
Compare lakeside cabins, hotels, and vacation rentals near Turtle Flambeau Flowage Lake in Iron 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.
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Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Turtle Flambeau Flowage Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (33,113 cells/mL) on May 9, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~16 ft est. |
| Surface Area | 13,798 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Wisconsin has not published bathymetry for Turtle Flambeau Flowage 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
- FishermansPublic
Fishing Turtle Flambeau Flowage Lake
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Turtle Flambeau Flowage 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).
- 2024Turtle Flambeau Flowage summer netting survey, 2024Netting Survey · WI DNR · 2024 (PDF)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.085 m/yr | 7 |
| Phosphorus | ↑ Improving | -0.48 µg/L/yr | 7 |
Reservoir Info (USACE NID)
Turtle Flambeau Flowage Lake is a man-made reservoir impounded by the Turtle-Flambeau (completed 1926), built primarily for hydroelectric on the North Fork Flambeau; concrete-type dam, 26 ft tall and 9,150 ft long.
- Surface area
- 13,798 ac
- Normal storage
- 135,000 ac-ft
- Max storage
- 239,000 ac-ft
- Drainage area
- 666 sq mi
- Hazard class
- High
- Owner
- Chippewa and Flambeau Improvement Company
Source: USACE National Inventory of Dams, NID ID WI00041 · Operator website
EPA Impairment Status
Turtle Flambeau Flowage Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10026777 · Official waterbody report
County Ranking
Ranked #4 of 16 lakes in Iron County
Nearby Lakes in Iron County
Frequently asked questions about Turtle Flambeau Flowage Lake
What is the water quality grade for Turtle Flambeau Flowage Lake?
- Turtle Flambeau Flowage Lake in Iron County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 19.4 µg/L. Surface area: 13798 acres.
Is Turtle Flambeau Flowage Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Turtle Flambeau Flowage Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Turtle Flambeau Flowage Lake?
- No published bathymetric survey covers Turtle Flambeau Flowage Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 16 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 13798 acres.
Does Turtle Flambeau Flowage Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Turtle Flambeau Flowage Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (33,113 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Turtle Flambeau Flowage Lake?
- Turtle Flambeau Flowage Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Fishermans. Public access is listed as yes.
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Where this data comes from
327 measurements from 7 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_WQX327 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (7)
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