Flour Lake
Cook County, Minnesota330 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Flour Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- spiny waterflea
- 75 ft max depth
- Public access
- Limited data
Flour Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 18.2 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Maximum depth: 75 ft. Surface area: 330.13 acres.
Minnesota DNR's Standard Survey on July 17, 2023 caught 0.42 walleye per trap net at Flour Lake. Length samples in the latest survey that recorded them ran 6–29 inches. DNR survey details →
Flour Lake is a 330-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 75 feet. Overall water quality is improving over recent sampling years. The lake supports 9 documented fish species including cisco species, green sunfish, and lake trout. Public access is available. Compared to the 43 other monitored lakes in Cook County, Flour Lake ranks #21 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-09. Methodology: how these readings are compared.
Flour Lake covers about 330 acres in Cook County. For a place on the water, look through cabin and lake-house rentals near Flour Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Flour Lake is good for
From access and monitoring records, not editorial picks.
- Clear water18.2 ft of visibility
- Fishing9 species recorded
- Deep water75 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Flour Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Flour Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Flour Lake
These are the measurements Minnesota PCA publishes for Flour Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 18.2 ft down. Phosphorus 7 µg/L. Chlorophyll-a 2.4 µg/L. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 18.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Flour Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Flour Lake typically sits around 58°F at the surface in September. Summer average is about 56°F. Usually warmest in Aug (about 58°F) and coldest in May (about 50°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (50°F) to its warmest (58°F).
Typical surface water temperature by month, from 326 field readings (2022–2025) via the EPA Water Quality Portal. See the full Flour Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 17, 2023 caught 0.42 walleye per trap net at Flour Lake. Length samples in the latest survey that recorded them ran 6–29 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Flour Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
14 surveys on file from MN DNR Fisheries. Most recent: 2025-08-13 (Targeted Survey).
14 surveys on file · most recent 2025-08-13 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Tullibee (Cisco) | 13.53 | 7–19 in 2023-07-17 | 1.09 lb |
| Yellow Perch | 2.11 | 1–8 in 2023-07-17 | 0.14 lb |
| Lake Trout | 1.70 | 7–8 in 2016-07-11 | 1.14 lb |
| Walleye | 1.52 | 6–29 in 2023-07-17 | 2.2 lb |
| Green Sunfish | 1.42 | 1–5 in 2023-07-17 | 0.07 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Tullibee (Cisco)
Yellow Perch
Lake Trout
Walleye
From the 2025-08-13 survey
Temperature and dissolved oxygen measurements were collected from the deepest basin in Flour Lake on August 13th, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout, the most sensitive coldwater species present in this lake (Cisco, also…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Flour Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — FlourFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Flour (1608)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — FlourFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — FlourPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
75 ft
Surface area
330 acres
Shoreline
8.5 mi
Littoral zone
35%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,732 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Flour Lake
Compare lakeside cabins, hotels, and vacation rentals near Flour Lake in Cook County, Minnesota — 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.
Top-rated places to stay near Flour Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fish Species
Click a species to see every lake where it is documented.
Fishing Flour Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Improving-2 µg/L/yr2 years
Chlorophyll-a
Improving-0.7 µg/L/yr2 years
EPA Impairment Status
Flour Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN16-0147-00 · Official waterbody report
Nearby Lakes in Cook County
Frequently asked questions about Flour Lake
Where is Flour Lake?
- Flour Lake is a lake in Cook County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Flour Lake?
- Flour Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 18.2 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Maximum depth: 75 ft. Surface area: 330.13 acres.
Is Flour Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Flour Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Flour Lake?
- Flour Lake typically sits around 58°F at the surface in September, from 326 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.
How deep is Flour Lake?
- Flour Lake has a maximum depth of 75 feet. The lake covers 330.13 acres.
What fish are in Flour Lake?
- Fish species found in Flour Lake include cisco species, green sunfish, lake trout, northern pike, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow perch. Flour Lake is located in Cook County, Minnesota.
What did the DNR fisheries survey find at Flour Lake?
- Minnesota DNR's Standard Survey on July 17, 2023 caught 0.42 walleye per trap net at Flour Lake. Length samples in the latest survey that recorded them ran 6–29 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Flour Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Flour Lake?
- Public access to Flour Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Flour Lake across LakeQuality
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Fish species and the cleanest lakes across Minnesota
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Species activity outlook by water temperature and season
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Where this data comes from
50 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA50 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder