Fish Lake
Kanabec County, MinnesotaLimited DataEutrophic
On the LakeGrade rubric Fish Lake fails the cutoffs — a TSI of 67 and persistent algal pressure put it in the bottom tier.
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. Fish Lake is a shallow lake at 8 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 506 acres, Fish Lake fits the Minnesota median for monitored lakes, with 10.0 miles of shoreline. Within the 7 graded lakes of Kanabec County, Fish Lake sits at rank 6, near the bottom of the county list.
Fish Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. Walleye are documented at Fish Lake, one of 21 fish species on record for the lake. A documented public access point at Fish Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 14 observed ice-outs, centered near Apr 19. 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 2024-10-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 2 ft of visibility. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8 ft |
| Surface Area | 506.41 acres |
| Shoreline Length | 10 mi |
| Littoral Zone | 99% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Fish Lake (14-day solunar calendar)
→ Is it safe to eat fish from Fish Lake? (mercury & PFAS guide)
→ Fish Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.159 m/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (24 observations).
Estimated open water season: 217 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-06 (2024) | 2018-04-30 (2018) |
| Ice-In | 2006-11-03 (2006) | 2025-12-02 (2025) |
Most recent ice-out: 2025-04-02
Location
County Ranking
Ranked #6 of 7 lakes in Kanabec County
Cleaner Lakes Within 30 Miles
Fish Lake holds Grade F. 3 nearby lakes hold higher grades.
Nearby Lakes in Kanabec County
More Minnesota Lake Rankings
State Parks Near Fish Lake
Other Grade F Lakes in Minnesota
Eutrophic Lakes in Minnesota
Compare Fish Lake With Nearby Lakes
DNR Fisheries Survey Summary
14 surveys on file from MN DNR Fisheries. Most recent: 2025-10-13 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Crappie | 32.34 | 0.33 lb |
| Largemouth Bass | 26.20 | 2.49 lb |
| Spottail Shiner | 18.69 | — |
| Bluegill | 14.83 | 0.3 lb |
| Walleye | 14.08 | 2.1 lb |
| CNM | 12.01 | — |
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
Largemouth Bass
Bluegill
Walleye
From the 2025-10-13 survey
Fish Lake is a 506-acre shallow impoundment on the Ann River in southern Kanabec County located four miles south of Mora and is within the Snake River Watershed. The lake has a maximum depth of 8 feet and an average depth of 5 feet. The lake is 100% littoral (15 feet or less, 506 acres). Water clarity is poor with…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Fish Lake. 4 reports on file.
- —Fisheries Lake Survey — FishFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Fish (0284)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — FishFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — FishPublic Water Access Sites · MN DNR LakeFinder
Reservoir Info (USACE NID)
Fish Lake is a man-made reservoir impounded by the Fish Lake (completed 1930), built primarily for other on the Ann River; gravity-type dam, 13 ft tall and 1,200 ft long.
- Surface area
- 440 ac
- Normal storage
- 2,442 ac-ft
- Max storage
- 3,663 ac-ft
- Drainage area
- 87 sq mi
- Hazard class
- Low
- Owner
- MNDNR-Fisheries and Wildlife
Source: USACE National Inventory of Dams, NID ID MN00572 · Operator website
EPA Impairment Status
Fish Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN33-0036-00 · 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: 2024-10-20
Monitoring stations: 1