Strup Lake
Lake County, MinnesotaLimited DataMesotrophic
Strup Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade.
A TSI near 44 places Strup Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake's 195 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. At 1,689 acres, Strup Lake is one of the larger lakes in Lake County, with 22.9 miles of shoreline supporting multiple distinct use patterns. Strup Lake sits at rank 104 of 142 in Lake County, in the lower half of the local distribution.
No invasive species are currently listed at Strup Lake — the lake remains off the Minnesota infested-waters roster. The fishery is bass-led, with 5 documented species across the lake's records. No formal public access is documented at Strup Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-07-08. Grade methodology: LakeGrade methodology.
Track Strup Lake
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 9.7 ft. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.7 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 195 ft |
| Surface Area | 1.7K acres |
| Shoreline Length | 22.9 mi |
| Littoral Zone | 6% |
| Public Access | No |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Strup Lake (14-day solunar calendar)
→ Is it safe to eat fish from Strup Lake? (mercury & PFAS guide)
→ Strup Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.793 m/yr | 4 |
Location
County Ranking
Ranked #104 of 142 lakes in Lake County
Nearby Lakes in Lake County
More Minnesota Lake Rankings
Other Grade C Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Compare Strup Lake With Nearby Lakes
DNR Fisheries Survey Summary
3 surveys on file from MN DNR Fisheries. Most recent: 2017-09-18 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Rock Bass | 12.50 | 0.13 lb |
| Lake Trout | 5.03 | 1.73 lb |
| Yellow Perch | 2.83 | 0.11 lb |
| White Sucker | 1.77 | 2.65 lb |
| DWS | 0.75 | — |
| SMS | 0.38 | — |
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.
Rock Bass
Lake Trout
Yellow Perch
White Sucker
From the 2017-09-18 survey
Kekekabic Lake is located approximately 31 miles NE of Ely in the BWCAW. This scenic lake has high cliffs and steep shorelines with good water clarity. There are several access options for visitors. All of these options include portages to access Kekekabic Lake and most visitors should allow more than one day to…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Strup Lake. 1 report on file.
- —Fisheries Lake Survey — KekekabicFisheries Lake Survey · MN DNR LakeFinder
EPA Impairment Status
Strup Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN38-0226-00 · Official waterbody report · Matched by proximity (2.66 km)
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: 2023-07-08
Monitoring stations: 6