Knife Lake is a lake in Lake County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.

Can I fish at Knife Lake?

Public access to Knife 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.

Knife Lake

Lake County, Minnesota105 acresView map Directions

Minnesota PCA publishes the water-quality measurements for Knife Lake. Here is what has been measured.

Clarity

20 ft

Clearer than most

Secchi · sampled 2025

Area

105 acres

Surface area

Trend

Worsening

6 years of samples

Shoreline

2.5 mi

Measured length

Impaired · Mercury
Limited data

See the measurements Directions Where to stay

Knife Lake in Lake County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 20 ft visibility. Surface area: 104.9 acres.

Minnesota DNR's Standard Survey on August 9, 1972 caught 5.60 northern pike per gill net at Knife Lake. DNR survey details →

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Knife Lake is a 105-acre lake in Lake County, Minnesota. 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 2025-09-19. Methodology: how these readings are compared.

What Knife Lake is good for

From access and monitoring records, not editorial picks.

Clear water20 ft of visibility

Swimming conditions

No reading

Limited data

Nutrient and algae readings are not a swimming clearance. Knife Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.

Whether Knife 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.

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Water quality measurements for Knife Lake

These are the measurements Minnesota PCA publishes for Knife 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 20 ft down. TSI 34.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	20ft	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.	34	Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Low nutrients, clear water. No reading is a swimming clearance.

Ask about Knife Lake

Answers come straight from the public measurements and survey records on this page.

DNR fisheries survey

Minnesota DNR's Standard Survey on August 9, 1972 caught 5.60 northern pike per gill net at Knife Lake.

A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Knife Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.

DNR Fisheries Survey Summary

1 survey on file from MN DNR Fisheries. Most recent: 1972-08-09 (Standard Survey).

1 survey on file · most recent 1972-08-09 (Standard Survey)

54 years old

Species	Catch rate (CPUE)	Avg weight
White Sucker	6.20	1.66 lb
Northern Pike	5.60	2.59 lb
Yellow Perch	1.40	0.16 lb
Pumpkinseed	1.00	0.06 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.

From the 1972-08-09 survey

Good population of northern pike; however, most are small (2-4 lbs). Sucker population is high and yellow perch population is low.

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Knife Lake. 1 report on file.

These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).

—
Fisheries Lake Survey — Bonnie
Fisheries Lake Survey · MN DNR LakeFinder

Lake Details

Surface area

105 acres

Shoreline

2.5 mi

Littoral zone

100%

Share shallower than 15 ft

Public access

Listed by Minnesota PCA

The available depth estimate for Knife Lake is shallower than its measured water clarity, which cannot be right, so no depth is shown.

Stays via Stay22

Stays near Knife Lake

Compare lakeside cabins, hotels, and vacation rentals near Knife Lake in Lake 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 Knife Lake

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Fishing Knife Lake

Water Quality Trend: Worsening

Based on 6 years of monitoring (2020–2025).

Water clarity
Worsening
6 years

See year-by-year chart →

EPA Impairment Status

Knife Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

Designated uses not supporting: Fish consumption.

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN38-0404-00 · Official waterbody report

Nearby Lakes in Lake County

Spoon Lake—View →Spoon Lake13 ft clear—View →Bonnie Lake8.2 ft clear—View →Pickle Lake12 ft clear—View →Knife Lake—View →Kettle Lake—View →

Frequently asked questions about Knife Lake

Where is Knife Lake?: Knife Lake is a lake in Lake County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Knife Lake?: Knife Lake in Lake County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 20 ft visibility. Surface area: 104.9 acres.
Is Knife Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Knife Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
How deep is Knife Lake?: The available depth estimate for Knife Lake is shallower than its measured water clarity, which cannot be right, so no depth is shown. The lake covers 104.9 acres.
What did the DNR fisheries survey find at Knife Lake?: Minnesota DNR's Standard Survey on August 9, 1972 caught 5.60 northern pike per gill net at Knife Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Knife Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Knife Lake?: Public access to Knife 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.

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Where this data comes from

140 measurements from 42 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 WaterMNPCA140 samples · 2020–2025

Analytical methods

Field measurement/observation, generic method

Monitoring station identifiers (42)

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.