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LakeQuality

Circle Lake

F
Grade F — Algae-prone
Algae-prone · #6 of 14 lakes in the county · 1.5 ft clear · Hypereutrophic · 838 acres
Limited DataHypereutrophic

Circle Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.5 ft visibility. Phosphorus: 484.5 µg/L. Chlorophyll-a (algae): 59.7 µg/L. Maximum depth: 14 ft. Surface area: 837.58 acres.

Clarity
1.5 ft
Typical in August
78°F
Max depth
14 ft
Area
838 acres
Type
Hypereutrophic
Trend
Declining
Public access
Yes
Ice-out
Mar 29
Open water
247 days

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

Next lake in Rice County

FFox Lake3 ft clear · Rice CountyView →
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Free interactive depth-contour map of Circle Lake, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.

Circle Lake is a 838-acre highly nutrient-loaded hypereutrophic lake in Rice County, Minnesota with a maximum depth of 14 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 18 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 13 other monitored lakes in Rice County, Circle Lake ranks #6 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 Circle Lake

Water Quality Grade: F (Algae-prone)

Very murky, less than 1.5 ft of visibility. Phosphorus level: 484.5 µg/L. Chlorophyll-a: 59.7 µg/L. Trophic State Index: 79.

MetricValueGrade
Water Clarity (Secchi Depth)1.5 ftNot graded
Phosphorus484.5 µg/LPoor
Chlorophyll-a (Algae)59.7 µg/LPoor
Trophic State Index (TSI)79Hypereutrophic

Very high nutrients, dense algae, poor clarity

Where to stay near Circle Lake

Compare lakeside cabins, hotels, and vacation rentals near Circle Lake in Rice 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 Circle Lake are listed below.

Top-rated places to stay near Circle 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

Circle Lake typically sits around 78°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 80°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
61°
Jun
73°
Jul
80°
Aug
78°
Sep
73°
Oct
Nov
Dec

Typical surface water temperature by month, from 69 field readings (20112025) via the EPA Water Quality Portal. See the full Circle Lake water temperature breakdown →

Lake Details

CharacteristicValue
Maximum Depth14 ft
Surface Area838 acres
Shoreline Length9.5 mi
Littoral Zone100%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
29 sq mi
Elevation
1,004 ft

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

Recreation & Access

1
Boat Landings
Yes
Public Access
  • Circle LakePublic

Fish Species

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

Fishing Circle 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

12 surveys on file from MN DNR Fisheries. Most recent: 2023-06-12 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Bullhead124.080.4 lb
Black Crappie27.020.29 lb
Yellow Perch23.710.2 lb
Common Carp7.963.86 lb
Bluegill6.700.24 lb
Freshwater Drum5.180.97 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 Bullhead

1,973 fish · 313 in · 2023-06-12
15227610345678910111213

Black Crappie

8 fish · 48 in · 2023-06-12
42045678

Yellow Perch

61 fish · 47 in · 2023-06-12
351804567

Common Carp

5 fish · 224 in · 2023-06-12
21024681012141618202224

From the 2023-06-12 survey

Circle Lake is an 838-acre lake located in Rice County northeast of Shieldsville. The lake has a maximum depth of 14 feet. There are three islands on Circle Lake, one of which is designated as an Aquatic Management Area by the MN DNR. A DNR-maintained public access is located on the northwest end of the lake. A public…

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 Circle Lake. 3 reports 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 Declining-0.093 m/yr6
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (21 observations).

Typical Ice-Out
Mar 29
Typical Ice-In
Dec 1

Estimated open water season: 247 days

EarliestLatest
Ice-Out2024-03-03 (2024)2013-04-28 (2013)
Ice-In2022-11-19 (2022)2001-12-18 (2001)

Most recent ice-out: 2025-03-16

EPA Impairment Status

Circle 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 MN66-0027-00 · Official waterbody report

County Ranking

Ranked #6 of 14 lakes in Rice County

Nearby Lakes With Higher Grades

Circle 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 Rice County

Frequently asked questions about Circle Lake

What is the water quality grade for Circle Lake?

Circle Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.5 ft visibility. Phosphorus: 484.5 µg/L. Chlorophyll-a (algae): 59.7 µg/L. Maximum depth: 14 ft. Surface area: 837.58 acres.

Is Circle 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. Circle Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 59.7 µg/L. Always check local health department advisories before swimming.

What is the water temperature of Circle Lake?

Circle Lake typically sits around 78°F at the surface in August, from 69 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.

How deep is Circle Lake?

Circle Lake has a maximum depth of 14 feet. The lake covers 837.58 acres.

What fish are in Circle Lake?

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

When does Circle Lake thaw?

Circle Lake typically has ice-out around Mar 29. Ice typically forms around Dec 1. The open water season is approximately 247 days.

Are there boat ramps on Circle Lake?

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

Hypereutrophic Lakes in Minnesota

Where this data comes from

117 measurements from 4 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 WaterMNPCA117 samples · 2020–2025

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by Colorimetry
  • 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (4)

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