Knife Lake

Not yet rated

20 ft clear · Oligotrophic · 105 acres

Limited DataOligotrophic

Knife Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 20 ft visibility. Surface area: 104.9 acres.

Clarity: 20 ft
Area: 105 acres
Trend: ↓ Declining
Public access: No

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Why Knife Lake has no grade

We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Knife Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).

Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.

Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.

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. Grade methodology: LakeGrade methodology.

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Swimming Safety

Not rated

Limited data

Not rated for swimming — there is not enough monitoring data to judge this lake

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Water quality measurements for Knife Lake

These readings exist but do not meet the evidence bar for an A–F grade — see why.

Crystal clear, you can see 20 ft down. Trophic State Index: 34.

Metric	Value	Grade
Water Clarity (Secchi Depth)	20 ft	Not graded
Phosphorus	No recent samples
Chlorophyll-a (Algae)	No recent samples
Trophic State Index (TSI)	34	Oligotrophic

Low nutrients, clear water, excellent for swimming

Where to stay 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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Lake Details

Characteristic	Value
Surface Area	105 acres
Shoreline Length	2.5 mi
Littoral Zone	100%
Public Access	No

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

Lake Size & Watershed

Watershed (drainage) area

997 sq mi

Elevation

1,378 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).

Fishing Knife Lake

→ Knife Lake fishing regulations (limits, seasons, special rules)

DNR Fisheries Survey Summary

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

Top Species by Catch Rate

Species	Avg 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, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.

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

Water Quality Trend: ↓ Declining

Based on 6 years of monitoring data (2020-2025).

Metric	Trend	Change/Year	Years
Water Clarity	↓ Declining	-0.472 m/yr	6

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

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

NRSpoon Lake13 ft clearView →NRBonnie Lake8.2 ft clearView →NRPickle Lake12 ft clearView →NRDix Lake14 ft clearView →NRKekekabic Lake19 ft clearView →NRKek Lake19.5 ft clearView →

Frequently asked questions about Knife Lake

What is the water quality grade for Knife Lake?: Knife Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 20 ft visibility. Surface area: 104.9 acres.
Is Knife Lake safe to swim in?: Not rated for swimming — there is not enough monitoring data to judge this lake. Knife Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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.

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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)

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