Flour Lake
Flour Lake in Cook County, Minnesota has a water quality grade of A (Excellent). 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.
- Clarity
- 18.2 ft
- Typical in August
- 58°F
- Max depth
- 75 ft
- Area
- 330 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Cook County
Flour Lake is a 330-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 75 feet. Water quality is graded A based on 2 sampling years through 2025. 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 with 2 public boat landings. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 18.2 ft down. Phosphorus level: 7 µg/L. Chlorophyll-a: 2.4 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18.2 ft | Not graded |
| Phosphorus | 7 µg/L | Good |
| Chlorophyll-a (Algae) | 2.4 µg/L | Good |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay 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.
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Water Temperature
Flour Lake typically sits around 58°F at the surface in August. 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.
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 →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 75 ft |
| Surface Area | 330 acres |
| Shoreline Length | 8.5 mi |
| Littoral Zone | 35% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- East Bearskin LakePublic
- West Bearskin LakePublic
Fish Species
Click a species to see every graded 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.
DNR Fisheries Survey Summary
14 surveys on file from MN DNR Fisheries. Most recent: 2025-08-13 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Tullibee (Cisco) | 13.53 | 1.09 lb |
| CIS | 8.84 | 1.43 lb |
| Yellow Perch | 2.11 | 0.14 lb |
| Lake Trout | 1.70 | 1.14 lb |
| Walleye | 1.52 | 2.2 lb |
| Green Sunfish | 1.42 | 0.07 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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)
CIS
Yellow Perch
Lake Trout
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
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.578 m/yr | 6 |
| Phosphorus | ↑ Improving | -2 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -0.7 µg/L/yr | 2 |
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN16-0147-00 · Official waterbody report
County Ranking
Ranked #21 of 44 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Flour Lake
What is the water quality grade for Flour Lake?
- Flour Lake in Cook County, Minnesota has a water quality grade of A (Excellent). 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?
- Excellent for swimming, crystal clear water with minimal algae. Flour Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.4 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Flour Lake?
- Flour Lake typically sits around 58°F at the surface in August, 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.
Are there boat ramps on Flour Lake?
- Flour Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include East Bearskin Lake, West Bearskin Lake. Public access is listed as yes.
Explore Flour Lake across LakeGrade
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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)
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)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory