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LakeQuality

Clearwater Lake

A
Grade A — Excellent
Excellent · #1 of 44 lakes in the county · 29 ft clear · Oligotrophic · 462 acres
Oligotrophic

Clearwater Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 29 ft visibility. Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Maximum depth: 65 ft. Surface area: 461.73 acres.

Clarity
29 ft
Max depth
65 ft
Area
462 acres
Type
Oligotrophic
Trend
Stable
Public access
No

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AFlour Lake18.2 ft clear · Cook CountyView →
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Clearwater Lake is a 462-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 65 feet. Water quality is graded A based on 2 sampling years through 2025. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 43 other monitored lakes in Cook County, Clearwater Lake ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-17. Grade methodology: LakeGrade methodology.

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Swimming Safety

Grade only

Low algae

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

Compare the safest swimming lakes near Ely

Get alerts for Clearwater Lake

Water Quality Grade: A (Excellent)

Crystal clear, you can see 29 ft down. Phosphorus level: 4 µg/L. Chlorophyll-a: 1.3 µg/L. Trophic State Index: 29.

MetricValueGrade
Water Clarity (Secchi Depth)29 ftNot graded
Phosphorus4 µg/LGood
Chlorophyll-a (Algae)1.3 µg/LGood
Trophic State Index (TSI)29Oligotrophic

Low nutrients, clear water, excellent for swimming

Where to stay near Clearwater Lake

Compare lakeside cabins, hotels, and vacation rentals near Clearwater 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.

Top-rated places to stay near Clearwater Lake

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Planning a whole trip? See where to stay at Minnesota’s top lakes →

Lake Details

CharacteristicValue
Maximum Depth65 ft
Surface Area462 acres
Shoreline Length8.1 mi
Public AccessNo

Fishing Clearwater 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.

spiny waterflea

DNR Fisheries Survey Summary

4 surveys on file from MN DNR Fisheries. Most recent: 2025-08-13 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
LKW10.673.59 lb
Walleye2.672.36 lb
White Sucker0.831.35 lb
Northern Pike0.675.49 lb
BUB0.331.53 lb
Smallmouth Bass0.171.44 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.

LKW

64 fish · 1623 in · 2000-07-17
201001617181920212223

Walleye

16 fish · 722 in · 2000-07-17
530810121416182022

White Sucker

5 fish · 920 in · 2000-07-17
21091011121314151617181920

Northern Pike

4 fish · 1741 in · 2000-07-17
210trophy 36182022242628303234363840

From the 2025-08-13 survey

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Caribou Lake on August 13th, 2025, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Whitefish, the only coldwater species present in this lake. During the summer, Lake…

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 Clearwater Lake. 1 report on file.

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

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

MetricTrendChange/YearYears
Water Clarity Stable-0.139 m/yr6
Phosphorus Stable-0.04 µg/L/yr6
Chlorophyll-a Stable+0.01 µg/L/yr6
See year-by-year chart →

EPA Impairment Status

Clearwater 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 MN16-0139-00 · Official waterbody report

County Ranking

Ranked #1 of 44 lakes in Cook County

Nearby Lakes in Cook County

Frequently asked questions about Clearwater Lake

What is the water quality grade for Clearwater Lake?

Clearwater Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 29 ft visibility. Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Maximum depth: 65 ft. Surface area: 461.73 acres.

Is Clearwater Lake safe to swim in?

Excellent for swimming, crystal clear water with minimal algae. Clearwater Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.3 µg/L. Always check local health department advisories before swimming.

How deep is Clearwater Lake?

Clearwater Lake has a maximum depth of 65 feet. The lake covers 461.73 acres.

Oligotrophic Lakes in Minnesota

Where this data comes from

215 measurements from 7 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 WaterMNPCA215 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 (7)

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 details from Minnesota DNR LakeFinder