Karl Lake
Cook County, Minnesota121 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Karl Lake. Here is what has been measured.
- 70 ft max depth
- Limited data
Karl Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8 ft visibility. Maximum depth: 70 ft. Surface area: 121.12 acres.
Minnesota DNR's Standard Survey on September 3, 1996 caught 1.67 northern pike per gill net at Karl Lake. Length samples in the latest survey that recorded them ran 12–29 inches. DNR survey details →
Karl Lake is a 121-acre lake in Cook County, Minnesota with a maximum depth of 70 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-07-21. Methodology: how these readings are compared.
What Karl Lake is good for
From access and monitoring records, not editorial picks.
- Deep water70 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 Karl 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 Karl Lake
These are the measurements Minnesota PCA publishes for Karl Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8 ft. TSI 47.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8ft | 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. | 47 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Karl Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on September 3, 1996 caught 1.67 northern pike per gill net at Karl Lake. Length samples in the latest survey that recorded them ran 12–29 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Karl Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2025-08-05 (Targeted Survey).
2 surveys on file · most recent 2025-08-05 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| White Sucker | 4.00 | 8–20 in 1996-09-03 | 2.38 lb |
| Northern Pike | 1.67 | 12–29 in 1996-09-03 | 1.54 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.
White Sucker
Northern Pike
From the 2025-08-05 survey
Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Karl Lake on August 5th, 2025, 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. During the summer,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Karl Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — KarlFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
70 ft
Surface area
121 acres
Shoreline
5.4 mi
Littoral zone
58%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
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Stays near Karl Lake
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Follow Karl Lake’s readings
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Fishing Karl Lake
Water quality readings over time
2 seasons of samples on record (2022–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Nearby Lakes in Cook County
Frequently asked questions about Karl Lake
Where is Karl Lake?
- Karl 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 Karl Lake?
- Karl Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8 ft visibility. Maximum depth: 70 ft. Surface area: 121.12 acres.
Is Karl Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Karl Lake?
- Karl Lake has a maximum depth of 70 feet. The lake covers 121.12 acres.
What did the DNR fisheries survey find at Karl Lake?
- Minnesota DNR's Standard Survey on September 3, 1996 caught 1.67 northern pike per gill net at Karl Lake. Length samples in the latest survey that recorded them ran 12–29 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Karl Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Karl Lake?
- Public access to Karl 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 Karl Lake across LakeQuality
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Where this data comes from
1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA1 sample · 2022
Analytical methods
- Field measurement/observation, generic method
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
Lake details from Minnesota DNR LakeFinder