Medicine Lake
Hennepin County, MinnesotaEutrophic
The LakeGrade rubric puts Medicine Lake at a C: clarity at 8.2 ft, 74 µg/L of phosphorus, and a TSI of 57 signal an intermediate trophic state. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.
A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. Medicine Lake reaches 49 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Medicine Lake covers 924 acres alongside 8.8 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 95 graded lakes in Hennepin County, Medicine Lake ranks 20 — in the top quartile locally.
Zebra mussels have been documented at Medicine Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Medicine Lake, one of 15 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 141 observations on file, with a median ice-out around Apr 10. 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 2024-10-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 8.2 ft. Phosphorus level: 74.2 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.2 ft | C |
| Phosphorus | 74.2 µg/L | D |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 49 ft |
| Surface Area | 924.36 acres |
| Shoreline Length | 8.8 mi |
| Littoral Zone | 43% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Medicine Lake (14-day solunar calendar)
→ Is it safe to eat fish from Medicine Lake? (mercury & PFAS guide)
→ Medicine 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.
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.191 m/yr | 5 |
| Phosphorus | ↓ Declining | +14.45 µg/L/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (257 observations).
Estimated open water season: 234 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-07 (2024) | 2018-05-02 (2018) |
| Ice-In | 1991-11-07 (1991) | 1998-12-21 (1998) |
Most recent ice-out: 2025-03-23
Location
County Ranking
Ranked #20 of 95 lakes in Hennepin County
Cleaner Lakes Within 30 Miles
Medicine Lake holds Grade C. 3 nearby lakes hold higher grades.
- BSweeney-Twin LakeHennepin County · mi · Higher grade (C → B)
- CWestwood LakeHennepin County · mi · Higher overall water quality score
- CParkers LakeHennepin County · mi · Higher overall water quality score
Nearby Lakes in Hennepin County
More Minnesota Lake Rankings
State Parks Near Medicine Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
Compare Medicine Lake With Nearby Lakes
DNR Fisheries Survey Summary
15 surveys on file from MN DNR Fisheries. Most recent: 2023-07-05 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 24.96 | 0.18 lb |
| BKF | 18.21 | — |
| Bluntnose Minnow | 9.80 | — |
| Black Crappie | 8.40 | 0.17 lb |
| Yellow Bass | 6.30 | 0.82 lb |
| Northern Pike | 5.92 | 2.53 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
Black Crappie
Yellow Bass
Northern Pike
From the 2023-07-05 survey
Medicine Lake is a 924-acre lake surrounded by the cities of Plymouth and Medicine Lake. Clifton E. French Regional Park (a Three Rivers Parks District property) borders the northwest portion of the lake and provides the only public boat launch during the open-water season; a fee is charged for parking boat…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Medicine Lake. 3 reports on file.
- —Fisheries Lake Survey — MedicineFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — MedicineFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — MedicinePublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Medicine Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN27-0104-00 · 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: 2024-10-12
Monitoring stations: 2