Clear Lake
Clear Lake in Aitkin County, Minnesota has a water quality grade of A (Excellent). Water clarity: 15 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Maximum depth: 24 ft. Surface area: 573.5 acres.
- Clarity
- 15 ft
- Typical in August
- 72°F
- Max depth
- 24 ft
- Area
- 574 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 17
- Open water
- 214 days
Next lake in Aitkin County
Clear Lake is a 574-acre mesotrophic lake in Aitkin County, Minnesota with a maximum depth of 24 feet (6-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 14 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 1 public boat landing. Compared to the 17 other monitored lakes in Aitkin County, Clear Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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
Water Quality Grade: A (Excellent)
Crystal clear, you can see 15 ft down. Phosphorus level: 13 µg/L. Chlorophyll-a: 4.3 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 15 ft | Not graded |
| Phosphorus | 13 µg/L | Good |
| Chlorophyll-a (Algae) | 4.3 µg/L | Good |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Clear Lake
Compare lakeside cabins, hotels, and vacation rentals near Clear Lake in Aitkin 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.
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Water Temperature
Clear Lake typically sits around 72°F at the surface in August. Summer average is about 70°F. Usually warmest in Jul (about 72°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 73 field readings (2016–2024) via the EPA Water Quality Portal. See the full Clear Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Clear Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (139,316 cells/mL) on May 30, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 24 ft |
| Average Depth | 6 ft |
| Surface Area | 574 acres |
| Shoreline Length | 5.3 mi |
| Littoral Zone | 63% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Clear LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Clear Lake
DNR Fisheries Survey Summary
19 surveys on file from MN DNR Fisheries. Most recent: 2025-07-28 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 39.69 | — |
| Bluegill | 30.57 | 0.18 lb |
| Yellow Bass | 14.69 | 0.37 lb |
| CNM | 8.72 | — |
| Spottail Shiner | 8.16 | — |
| IOD | 7.53 | — |
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.
Bluegill
Yellow Bass
From the 2025-07-28 survey
A targeted survey of nearshore fish species in Clear Lake was conducted on July 28-30, 2025, by Lake Biological Monitoring and Assessment (LBMA) program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible.…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Clear Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — ClearFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Clear (0001)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — ClearFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ClearPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.173 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (42 observations).
Estimated open water season: 214 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2000-03-25 (2000) | 2013-05-10 (2013) |
| Ice-In | 1991-11-04 (1991) | 2001-12-21 (2001) |
Most recent ice-out: 2023-05-03
EPA Impairment Status
Clear Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN01-0093-00 · Official waterbody report
County Ranking
Ranked #2 of 18 lakes in Aitkin County
Nearby Lakes in Aitkin County
Frequently asked questions about Clear Lake
What is the water quality grade for Clear Lake?
- Clear Lake in Aitkin County, Minnesota has a water quality grade of A (Excellent). Water clarity: 15 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Maximum depth: 24 ft. Surface area: 573.5 acres.
Is Clear Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Clear Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Clear Lake?
- Clear Lake typically sits around 72°F at the surface in August, from 73 EPA Water Quality Portal field readings (2016–2024). That is a typical value for the month, not a live reading.
How deep is Clear Lake?
- Clear Lake has a maximum depth of 24 feet and an average depth of 6 feet. The lake covers 573.5 acres.
What fish are in Clear Lake?
- Fish species found in Clear Lake include black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Clear Lake is located in Aitkin County, Minnesota.
When does Clear Lake thaw?
- Clear Lake typically has ice-out around Apr 17. Ice typically forms around Nov 17. The open water season is approximately 214 days.
Does Clear Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Clear Lake (clouds, ice, or an off-season gap). The most recent reading was high (139,316 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Clear Lake?
- Clear Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Clear Lake. Public access is listed as yes.
Explore Clear Lake across LakeGrade
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Where this data comes from
66 measurements from 2 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
MNPCA66 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (2)
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
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate