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C

Wirth Lake

Hennepin County, MinnesotaMesotrophic

Wirth Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

Mesotrophic conditions dominate at Wirth Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Wirth Lake reaches 25 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Wirth Lake is small — 40 acres alongside 1.2 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Among the 95 graded lakes in Hennepin County, Wirth Lake ranks 17 — in the top quartile locally.

Eurasian watermilfoil is established at Wirth Lake, which can dampen recreational access and pressure the native plant community. Bass fishing is part of the appeal: the species list runs to 9, anchored by largemouth and/or smallmouth bass. A documented public access point at Wirth Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been logged at Wirth Lake more than two dozen times, putting the median around Apr 4 — a useful baseline for tracking climate trends. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-18. 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

Moderate clarity, visible to about 9.7 ft. Phosphorus level: 31.5 µg/L. Trophic State Index: 49.

MetricValueGrade
Water Clarity (Secchi Depth)9.7 ftC
Phosphorus31.5 µg/LC
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)49Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth25 ft
Surface Area39.97 acres
Shoreline Length1.2 mi
Littoral Zone58%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,hybrid sunfish,largemouth bass,northern pike,pumpkinseed,white sucker,yellow bullhead

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

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

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

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

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

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Improving+0.244 m/yr5
Phosphorus Improving-4.15 µg/L/yr4
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (140 observations).

Typical Ice-Out
Apr 4
Typical Ice-In
Nov 26

Estimated open water season: 236 days

EarliestLatest
Ice-Out2024-03-04 (2024)2013-04-27 (2013)
Ice-In1991-11-04 (1991)2024-01-16 (2024)

Most recent ice-out: 2024-03-04

Location

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County Ranking

Ranked #17 of 95 lakes in Hennepin County

Cleaner Lakes Within 30 Miles

Wirth Lake holds Grade C. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Hennepin County

DNR Fisheries Survey Summary

9 surveys on file from MN DNR Fisheries. Most recent: 2018-08-07 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Crappie54.010.16 lb
Black Bullhead40.040.35 lb
Bluegill22.220.12 lb
Yellow Perch4.200.09 lb
Channel Catfish4.040.9 lb
Pumpkinseed3.310.11 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

12 fish · 57 in · 2018-08-07
950567

Black Bullhead

4 fish · 611 in · 2018-08-07
21067891011

Bluegill

371 fish · 36 in · 2018-08-07
1517603456

Yellow Perch

8 fish · 66 in · 2012-08-27
8406

From the 2018-08-07 survey

Wirth Lake is part of Fishing in the Neighborhood (FiN). It is located within the city limits of Golden Valley but is surrounded by Theodore Wirth Park which is administered by the City of Minneapolis. Wirth Lake has a public fishing pier and boat launch that provide access for fishing. Bluegill abundance was…

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 Wirth Lake. 3 reports on file.

EPA Impairment Status

Wirth Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

MercurySalinity / chlorides

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

Source: EPA ATTAINS assessment unit MN27-0037-00 · 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

Ice data from Minnesota DNR Climate

Most recent sample: 2024-09-18

Monitoring stations: 1