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LakeQuality

Duck Lake

F
Grade F — Algae-prone
Algae-prone · #5 of 5 lakes in the county · 2.8 ft clear · Eutrophic · 290 acres
Limited DataEutrophic

Duck Lake in Blue Earth County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.8 ft visibility. Phosphorus: 105 µg/L. Chlorophyll-a (algae): 31.5 µg/L. Maximum depth: 25 ft. Surface area: 290.42 acres.

Clarity
2.8 ft
Typical in August
77°F
Max depth
25 ft
Area
290 acres
Type
Eutrophic
Trend
Stable
Public access
Yes
Ice-out
Apr 4
Open water
241 days

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

Next lake in Blue Earth County

DBallantyne Lake2.5 ft clear · Blue Earth CountyView →
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Duck Lake is a 290-acre productive, nutrient-rich eutrophic lake in Blue Earth County, Minnesota with a maximum depth of 25 feet. Water quality is graded F based on 2 sampling years through 2024. The lake supports 17 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 4 other monitored lakes in Blue Earth County, Duck Lake ranks #5 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-25. 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 Duck Lake

Water Quality Grade: F (Algae-prone)

Very murky, less than 2.8 ft of visibility. Phosphorus level: 105 µg/L. Chlorophyll-a: 31.5 µg/L. Trophic State Index: 66.

MetricValueGrade
Water Clarity (Secchi Depth)2.8 ftNot graded
Phosphorus105 µg/LPoor
Chlorophyll-a (Algae)31.5 µg/LPoor
Trophic State Index (TSI)66Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Duck Lake

Compare lakeside cabins, hotels, and vacation rentals near Duck Lake in Blue Earth 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 Duck Lake are listed below.

Top-rated places to stay near Duck 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

Duck Lake typically sits around 77°F at the surface in August. Summer average is about 73°F. Usually warmest in Aug (about 77°F) and coldest in May (about 60°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
60°
Jun
70°
Jul
73°
Aug
77°
Sep
69°
Oct
Nov
Dec

Typical surface water temperature by month, from 59 field readings (20162024) via the EPA Water Quality Portal. See the full Duck Lake water temperature breakdown →

Lake Details

CharacteristicValue
Maximum Depth25 ft
Surface Area290 acres
Shoreline Length2.7 mi
Littoral Zone80%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
4 sq mi
Elevation
1,010 ft

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

Recreation & Access

1
Boat Landings
Yes
Public Access
  • Duck LakePublic

Fish Species

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

Fishing Duck Lake

DNR Fisheries Survey Summary

12 surveys on file from MN DNR Fisheries. Most recent: 2022-06-14 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluntnose Minnow58.41
Bluegill36.720.2 lb
Black Bullhead31.940.63 lb
Largemouth Bass17.301.36 lb
SFS16.75
White Crappie13.510.32 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.

Bluegill

404 fish · 47 in · 2022-06-13
21210604567

Black Bullhead

882 fish · 911 in · 2022-06-13
746373091011

Largemouth Bass

23 fish · 518 in · 2022-06-13
53056789101112131415161718

White Crappie

372 fish · 512 in · 2022-06-13
167840trophy 1056789101112

From the 2022-06-14 survey

A targeted survey of nearshore fish species in Duck Lake was conducted on June 14-15, 2022, by DNR Index of Biological Integrity (IBI) 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. Backpack…

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 Duck Lake. 3 reports on file.

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

Based on 4 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Stable-0.001 m/yr4
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (73 observations).

Typical Ice-Out
Apr 4
Typical Ice-In
Dec 1

Estimated open water season: 241 days

EarliestLatest
Ice-Out2000-03-07 (2000)1988-04-30 (1988)
Ice-In1991-11-04 (1991)2024-01-07 (2024)

Most recent ice-out: 2023-04-12

EPA Impairment Status

Duck 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 MN07-0053-00 · Official waterbody report

County Ranking

Ranked #5 of 5 lakes in Blue Earth County

Nearby Lakes With Higher Grades

Duck Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.

Nearby Lakes in Blue Earth County

Frequently asked questions about Duck Lake

What is the water quality grade for Duck Lake?

Duck Lake in Blue Earth County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.8 ft visibility. Phosphorus: 105 µg/L. Chlorophyll-a (algae): 31.5 µg/L. Maximum depth: 25 ft. Surface area: 290.42 acres.

Is Duck 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. Duck Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 31.5 µg/L. Always check local health department advisories before swimming.

What is the water temperature of Duck Lake?

Duck Lake typically sits around 77°F at the surface in August, from 59 EPA Water Quality Portal field readings (2016–2024). That is a typical value for the month, not a live reading.

How deep is Duck Lake?

Duck Lake has a maximum depth of 25 feet. The lake covers 290.42 acres.

What fish are in Duck Lake?

Fish species found in Duck Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), common carp, freshwater drum, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, smallmouth buffalo, walleye, white crappie, white sucker, yellow bullhead, yellow perch. Duck Lake is located in Blue Earth County, Minnesota.

When does Duck Lake thaw?

Duck Lake typically has ice-out around Apr 4. Ice typically forms around Dec 1. The open water season is approximately 241 days.

Are there boat ramps on Duck Lake?

Duck Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Duck Lake. Public access is listed as yes.

Where this data comes from

26 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Minnesota Pollution Control Agency - Ambient Surface WaterMNPCA26 samples · 2023–2024

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by Colorimetry
  • 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)

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