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LakeQuality

Clear Lake

F
Grade F — Algae-prone
Algae-prone · #2 of 2 lakes in the county · 2.5 ft clear · Hypereutrophic · 649 acres
Limited DataHypereutrophic

Clear Lake in Waseca County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 151 µg/L. Chlorophyll-a (algae): 59.3 µg/L. Maximum depth: 34 ft. Surface area: 648.77 acres.

Clarity
2.5 ft
Typical in August
78°F
Max depth
34 ft
Area
649 acres
Type
Hypereutrophic
Trend
Declining
Public access
Yes
Ice-out
Apr 2
Open water
243 days

Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Clear Lake

Next lake in Waseca County

CLoon Lake2.5 ft clear · Waseca CountyView →
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Clear Lake is a 649-acre highly nutrient-loaded hypereutrophic lake in Waseca County, Minnesota with a maximum depth of 34 feet. Water quality is graded F based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 1 other monitored lakes in Waseca County, Clear Lake ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-28. Grade methodology: LakeGrade methodology.

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Swimming Safety

Grade only

Limited 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.

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom

Compare the safest swimming lakes near Mankato

Get alerts for Clear Lake

Water Quality Grade: F (Algae-prone)

Very murky, less than 2.5 ft of visibility. Phosphorus level: 151 µg/L. Chlorophyll-a: 59.3 µg/L. Trophic State Index: 70.

MetricValueGrade
Water Clarity (Secchi Depth)2.5 ftNot graded
Phosphorus151 µg/LPoor
Chlorophyll-a (Algae)59.3 µg/LPoor
Trophic State Index (TSI)70Hypereutrophic

Very high nutrients, dense algae, poor clarity

Where to stay near Clear Lake

Compare lakeside cabins, hotels, and vacation rentals near Clear Lake in Waseca 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Clear Lake are listed below.

Top-rated places to stay near Clear Lake

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

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

Water Temperature

Clear Lake typically sits around 78°F at the surface in August. Summer average is about 75°F. Usually warmest in Aug (about 78°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
56°
Jun
70°
Jul
77°
Aug
78°
Sep
71°
Oct
Nov
Dec

Typical surface water temperature by month, from 93 field readings (20222025) via the EPA Water Quality Portal. See the full Clear Lake water temperature breakdown →

Blue-Green Algae (Cyanobacteria)

No current satellite reading

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 (319,154 cells/mL) on July 19, 2026.

Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗

Lake Details

CharacteristicValue
Maximum Depth34 ft
Surface Area649 acres
Shoreline Length4.4 mi
Littoral Zone69%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
15 sq mi
Elevation
1,112 ft

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

Recreation & Access

2
Boat Landings
Yes
Public Access
  • Clear Lake (South)Public
  • Clear Lake (North)Public

Fish Species

Click a species to see every graded lake where it is documented.

Fishing Clear 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.

Eurasian watermilfoil

DNR Fisheries Survey Summary

24 surveys on file from MN DNR Fisheries. Most recent: 2024-08-05 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Crappie61.240.19 lb
Black Bullhead49.450.95 lb
Bluegill41.770.2 lb
Largemouth Bass23.971.63 lb
Yellow Perch11.910.18 lb
Freshwater Drum5.591.27 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.

Black Crappie

520 fish · 411 in · 2024-08-05
2661330trophy 104567891011

Black Bullhead

69 fish · 615 in · 2024-08-05
211106789101112131415

Bluegill

1,150 fish · 48 in · 2024-08-05
657329045678

Largemouth Bass

35 fish · 520 in · 2024-08-05
630trophy 2068101214161820

From the 2024-08-05 survey

Clear Lake is a 652-acre lake located within the town of Waseca in Waseca County. Two DNR-maintained public accesses are available. One is located off Clear Lake Drive on the north side and the other just off MN Highway 14 on the southeast side of the lake. The maximum depth is 34 feet with approximately 69% of the…

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 Clear Lake. 3 reports on file.

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

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.061 m/yr5
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (140 observations).

Typical Ice-Out
Apr 2
Typical Ice-In
Dec 1

Estimated open water season: 243 days

EarliestLatest
Ice-Out2024-03-01 (2024)2018-04-29 (2018)
Ice-In2022-11-20 (2022)2017-12-07 (2017)

Most recent ice-out: 2026-03-22

Reservoir Info (USACE NID)

Clear Lake is a man-made reservoir impounded by the Clear Lake (completed 1937), built primarily for recreation on the Crane Creek-TR; concrete-type dam, 8 ft tall and 18 ft long.

Surface area
611 ac
Normal storage
6,500 ac-ft
Max storage
7,900 ac-ft
Drainage area
38 sq mi
Hazard class
Low
Owner
County of Waseca

Source: USACE National Inventory of Dams, NID ID MN01455 · Operator website

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

MercuryNutrients (phosphorus, nitrogen)

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

Source: EPA ATTAINS assessment unit MN81-0014-01 · Official waterbody report

County Ranking

Ranked #2 of 2 lakes in Waseca County

Nearby Lakes in Waseca County

Frequently asked questions about Clear Lake

What is the water quality grade for Clear Lake?

Clear Lake in Waseca County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 151 µg/L. Chlorophyll-a (algae): 59.3 µg/L. Maximum depth: 34 ft. Surface area: 648.77 acres.

Is Clear Lake safe to swim in?

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Clear Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 59.3 µg/L. Always check local health department advisories before swimming.

What is the water temperature of Clear Lake?

Clear Lake typically sits around 78°F at the surface in August, from 93 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.

How deep is Clear Lake?

Clear Lake has a maximum depth of 34 feet. The lake covers 648.77 acres.

What fish are in Clear Lake?

Fish species found in Clear Lake include black bullhead, black crappie, bluegill, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. Clear Lake is located in Waseca County, Minnesota.

When does Clear Lake thaw?

Clear Lake typically has ice-out around Apr 2. Ice typically forms around Dec 1. The open water season is approximately 243 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 (319,154 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 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Clear Lake (South), Clear Lake (North). Public access is listed as yes.

Where this data comes from

109 measurements from 3 monitoring stations, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Minnesota Pollution Control Agency - Ambient Surface WaterMNPCA109 samples · 2021–2025

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by Colorimetry
  • 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (3)

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