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C

Horseshoe Lake

Chisago County, MinnesotaEutrophic

Horseshoe Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Secchi readings are the weakest of the scored parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake's 53 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. At 224 acres, Horseshoe Lake fits the Minnesota median for monitored lakes, with 4.1 miles of shoreline. Horseshoe Lake ranks 13 of 31 in Chisago County — solidly in the upper half of the local distribution.

No invasive species are currently listed at Horseshoe Lake — the lake remains off the Minnesota infested-waters roster. Bass fishing is part of the appeal: the species list runs to 14, anchored by largemouth and/or smallmouth bass. Public access is available — the lake is on the Minnesota PCA public-access list. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-24. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Murky, only visible to about 4.6 ft. Phosphorus level: 28.5 µg/L. Chlorophyll-a: 5.5 µg/L. Trophic State Index: 52.

MetricValueGrade
Water Clarity (Secchi Depth)4.6 ftD
Phosphorus28.5 µg/LB
Chlorophyll-a (Algae)5.5 µg/LB
Trophic State Index (TSI)52Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Maximum Depth53 ft
Average Depth13 ft
Surface Area224.04 acres
Shoreline Length4.1 mi
Littoral Zone50%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,bowfin (dogfish),brown bullhead,common carp,green sunfish,hybrid sunfish,largemouth bass,northern pike,pumpkinseed,white sucker,yellow bullhead,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Horseshoe Lake (14-day solunar calendar)

→ Is it safe to eat fish from Horseshoe Lake? (mercury & PFAS guide)

Horseshoe Lake fishing regulations (limits, seasons, special rules)

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Improving+0.05 m/yr5
Phosphorus Improving-4.4 µg/L/yr5
Chlorophyll-a Improving-6.65 µg/L/yr3
See year-by-year chart →

Location

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County Ranking

Ranked #13 of 31 lakes in Chisago County

Cleaner Lakes Within 30 Miles

Horseshoe Lake holds Grade C. 3 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Chisago County

DNR Fisheries Survey Summary

9 surveys on file from MN DNR Fisheries. Most recent: 2025-08-28 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Bullhead37.710.25 lb
CNM35.37
Bluegill21.870.2 lb
Green Sunfish10.710.07 lb
Largemouth Bass9.291.44 lb
Black Crappie8.920.18 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

5 fish · 810 in · 2025-06-02
2108910

Bluegill

271 fish · 37 in · 2025-06-02
10955034567

Green Sunfish

11 fish · 35 in · 2000-06-19
530345

Largemouth Bass

25 fish · 416 in · 2025-06-02
74045678910111213141516

From the 2025-08-28 survey

A targeted survey of nearshore fish species in Horseshoe Lake was conducted on August 28, 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…

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 Horseshoe Lake. 2 reports on file.

EPA Impairment Status

Horseshoe Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Impaired biota (cause unknown)Nutrients (phosphorus, nitrogen)

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

Source: EPA ATTAINS assessment unit MN13-0073-00 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Lake details from Minnesota DNR LakeFinder

Most recent sample: 2024-09-24

Monitoring stations: 1