Strup Lake
Strup Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10 ft visibility. Maximum depth: 195 ft. Surface area: 1688.66 acres.
- Clarity
- 10 ft
- Max depth
- 195 ft
- Area
- 1,689 acres
- Trend
- ↓ Declining
- Public access
- No
Next lake in Lake County
Why Strup Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Strup Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Strup Lake is a 1,689-acre lake in Lake County, Minnesota with a maximum depth of 195 feet. Overall water quality is declining over recent sampling years. The lake supports 5 documented fish species including lake trout, rock bass, and smallmouth bass. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Strup Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 10 ft. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Strup Lake
Compare lakeside cabins, hotels, and vacation rentals near Strup Lake in Lake 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.
Top-rated places to stay near Strup Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 195 ft |
| Surface Area | 1,689 acres |
| Shoreline Length | 22.9 mi |
| Littoral Zone | 6% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Strup Lake
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.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — KekekabicFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.354 m/yr | 5 |
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 (2.64 km)
Nearby Lakes in Lake County
Frequently asked questions about Strup Lake
What is the water quality grade for Strup Lake?
- Strup Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10 ft visibility. Maximum depth: 195 ft. Surface area: 1688.66 acres.
Is Strup Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Strup Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Strup Lake?
- Strup Lake has a maximum depth of 195 feet. The lake covers 1688.66 acres.
What fish are in Strup Lake?
- Fish species found in Strup Lake include lake trout, rock bass, smallmouth bass, white sucker, yellow perch. Strup Lake is located in Lake County, Minnesota.
Explore Strup Lake across LakeGrade
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Where this data comes from
13 measurements from 7 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 Water
MNPCA13 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (7)
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