Minnesota DNR fisheries surveys · latest August 26, 2002
Thomson Reservoir FishingNRNot rated for water quality
Minnesota DNR surveys at Thomson Reservoir average 2.40 walleye per unit of sampling effort (CPUE) across 2 surveys. The most recent is a Standard Survey dated August 26, 2002. Length samples in the latest survey that recorded them ran 7–18 inches. In Carlton County, Minnesota, Thomson Reservoir has no letter grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Water clarity averages 4.0 feet of visibility. The survey figures on this page are Minnesota DNR's own; the water-quality grade comes from EPA Water Quality Portal samples. Neither is a forecast of today's bite.
Species recorded at Thomson Reservoir
10 species on the Minnesota DNR list for this lake. A species on the list has been recorded here; it does not mean it is catchable today or in every part of the lake.
Stocking at Thomson Reservoir
No stocking record for Thomson Reservoir appears in the Minnesota DNR material on file. That is an absence in the published record, not a confirmation that the lake is unstocked — some waters are managed as naturally reproducing and never appear in a stocking list at all.
Survey results in full
Minnesota DNR surveys at Thomson Reservoir average 2.40 walleye per unit of sampling effort (CPUE) across 2 surveys. The most recent is a Standard Survey dated August 26, 2002. Length samples in the latest survey that recorded them ran 7–18 inches.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Thomson Reservoir — official chemistry is on file, not a letter. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2002-08-26 (Standard Survey).
Top Species by Catch Rate
| Species | Avg catch rate (CPUE) | Avg Weight |
|---|---|---|
| White Sucker | 9.05 | 1.48 lb |
| Walleye | 2.40 | 0.68 lb |
| Yellow Perch | 1.55 | 0.52 lb |
| Smallmouth Bass | 1.23 | 1.39 lb |
| Black Bullhead | 0.87 | 0.38 lb |
| Northern Pike | 0.84 | 1.54 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE means more abundant in standardized sampling. This is not a weekly bite report.
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.
White Sucker
Walleye
Yellow Perch
Smallmouth Bass
From the 2002-08-26 survey
Thomson is a 339 acre reservoir located immediately north of Thomson, MN. It is operated as a water storage reservoir by Minnesota Power for the Thomson Hydro Station further down stream and is subject to water level manipulation. Maximum depth is 22 feet and 83% of the reservoir is shallower than 15 feet. Access is…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Thomson Reservoir. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Thomson ReservoirFisheries Lake Survey · MN DNR LakeFinder
Common questions
What fish are in Thomson Reservoir?
Minnesota DNR surveys at Thomson Reservoir average 2.40 walleye per unit of sampling effort (CPUE) across 2 surveys. The most recent is a Standard Survey dated August 26, 2002. Length samples in the latest survey that recorded them ran 7–18 inches. Minnesota DNR lists 10 species for the lake in total. Those are survey results, not a catch report: a net set on one date measures what was in that net.
When was Thomson Reservoir last surveyed?
The most recent fisheries survey on file for Thomson Reservoir is dated August 26, 2002. Survey intervals vary by lake and by species; a gap of several years between surveys is normal and does not mean the record is missing.
Is Thomson Reservoir stocked?
No stocking record for Thomson Reservoir appears in the Minnesota DNR material on file. That is not the same as a confirmed unstocked lake: it means no stocking document was published for it in the records this page draws on.
Does the water-quality grade tell me how Thomson Reservoir fishes?
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Thomson Reservoir — official chemistry is on file, not a letter. Catch rate is not a swim clearance and is not a weekly bite report.
Before you eat what you catch
A water-quality grade is not a consumption advisory. Mercury and PCB advice for Minnesota waters comes from MDH, and it is issued per species and per size class — a lake can grade well and still carry a meal limit on larger predator fish.
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