Red Rock Lake
Cook County, Minnesota451 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Red Rock Lake. Here is what has been measured.
- spiny waterflea
- 64 ft max depth
- Limited data
Red Rock Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12 ft visibility. Maximum depth: 64 ft. Surface area: 450.9 acres.
Minnesota DNR's Standard Survey on July 10, 2023 caught 2.20 walleye per gill net at Red Rock Lake. Length samples in the latest survey that recorded them ran 10–24 inches. DNR survey details →
Red Rock Lake is a 451-acre lake in Cook County, Minnesota with a maximum depth of 64 feet. Overall water quality is declining over recent sampling years. The lake supports 8 documented fish species including burbot, lake whitefish, and northern pike. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-06-29. Methodology: how these readings are compared.
What Red Rock Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12 ft of visibility
- Fishing8 species recorded
- Deep water64 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Red Rock 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 Red Rock Lake
These are the measurements Minnesota PCA publishes for Red Rock Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 12 ft. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 12ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Red Rock Lake
Answers come straight from the public measurements and survey records on this page.
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Red Rock Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (469,894 cells/mL) on November 24, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Standard Survey on July 10, 2023 caught 2.20 walleye per gill net at Red Rock Lake. Length samples in the latest survey that recorded them ran 10–24 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Red Rock Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2025-08-07 (Targeted Survey).
7 surveys on file · most recent 2025-08-07 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Tullibee (Cisco) | 5.33 | 7–19 in 2023-07-10 | 0.92 lb |
| Walleye | 2.95 | 10–24 in 2023-07-10 | 1.9 lb |
| Northern Pike | 2.58 | 9–31 in 2023-07-10 | 2.75 lb |
| Yellow Perch | 1.69 | 0.16 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)
Walleye
Northern Pike
From the 2025-08-07 survey
Temperature and dissolved oxygen measurements were collected from the deepest basin in Red Rock Lake on August 7th, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Whitefish, the most sensitive coldwater species present in this lake…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Red Rock Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Red RockFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
64 ft
Surface area
451 acres
Shoreline
12.9 mi
Littoral zone
32%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
153 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,430 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Red Rock Lake
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Top-rated places to stay near Red Rock Lake
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Follow Red Rock Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Red Rock 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: Worsening
Based on 4 years of monitoring (2020–2025).
Water clarity
Worsening4 years
Nearby Lakes in Cook County
Frequently asked questions about Red Rock Lake
Where is Red Rock Lake?
- Red Rock 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 Red Rock Lake?
- Red Rock Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12 ft visibility. Maximum depth: 64 ft. Surface area: 450.9 acres.
Is Red Rock Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Red Rock Lake?
- Red Rock Lake has a maximum depth of 64 feet. The lake covers 450.9 acres.
What fish are in Red Rock Lake?
- Fish species found in Red Rock Lake include burbot, lake whitefish, northern pike, pumpkinseed, smallmouth bass, tullibee (cisco), walleye, white sucker. Red Rock Lake is located in Cook County, Minnesota.
What did the DNR fisheries survey find at Red Rock Lake?
- Minnesota DNR's Standard Survey on July 10, 2023 caught 2.20 walleye per gill net at Red Rock Lake. Length samples in the latest survey that recorded them ran 10–24 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Red Rock Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Does Red Rock Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Red Rock Lake (clouds, ice, or an off-season gap). The most recent reading was high (469,894 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Can I fish at Red Rock Lake?
- Public access to Red Rock Lake is listed as no on the lake record, so confirm before you make the trip. 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 Red Rock Lake across LakeQuality
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Where this data comes from
4 measurements from 4 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (4)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder