Ann Lake
Kanabec County, MinnesotaEutrophic
Ann Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota average. 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. The lake bottoms out at 17 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Ann Lake covers 653 acres alongside 11.4 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Kanabec County's 7 graded lakes, Ann Lake ranks 5 — below the local median, though not at the bottom.
No invasive species are currently listed at Ann Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye among the lake's 13 documented species — a notable draw for Minnesota anglers. A documented public access point at Ann Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a long ice-out record — 65 observations on file, with a median ice-out around Apr 16. 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 2024-08-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2 ft of visibility. Phosphorus level: 78.5 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | F |
| Phosphorus | 78.5 µg/L | D |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 17 ft |
| Surface Area | 653.49 acres |
| Shoreline Length | 11.4 mi |
| Littoral Zone | 92% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Ann Lake (14-day solunar calendar)
→ Is it safe to eat fish from Ann Lake? (mercury & PFAS guide)
→ Ann 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 | -0.07 m/yr | 2 |
| Phosphorus | ↓ Declining | +12.45 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (83 observations).
Estimated open water season: 219 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2000-03-25 (2000) | 2013-05-16 (2013) |
| Ice-In | 2003-11-08 (2003) | 1999-12-15 (1999) |
Most recent ice-out: 2019-04-22
Location
County Ranking
Ranked #5 of 7 lakes in Kanabec County
Cleaner Lakes Within 30 Miles
Ann Lake holds Grade D. 2 nearby lakes hold higher grades.
- BMl-Thains LakeMille Lacs County · mi · Two grade letters higher (D → B)
- CLory LakeIsanti County · mi · Higher grade (D → C)
Nearby Lakes in Kanabec County
More Minnesota Lake Rankings
State Parks Near Ann Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
Compare Ann Lake With Nearby Lakes
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2021-06-21 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 10.81 | 0.14 lb |
| Largemouth Bass | 9.96 | 1.44 lb |
| BLH | 9.31 | — |
| Bluegill | 6.66 | 0.3 lb |
| OTS | 6.30 | 2.02 lb |
| Black Crappie | 4.83 | 0.32 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.
Yellow Perch
Largemouth Bass
Bluegill
Black Crappie
From the 2021-06-21 survey
Ann Lake is a 653-acre lake located in Kanabec County managed primarily for Walleye and Northern Pike. The water level is maintained by a DNR dam on the north end of the lake. Lakeshore development is relatively light due largely to the wildlife management area on the southeast and northeast shores. Shallow water…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Ann Lake. 4 reports on file.
- —Fisheries Lake Survey — AnnFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Ann (0289)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — AnnFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — AnnPublic Water Access Sites · MN DNR LakeFinder
Reservoir Info (USACE NID)
Ann Lake is a man-made reservoir impounded by the Ann Lake (completed 1966), built primarily for fish and wildlife pond on the Ann River; other-type dam, 25 ft tall and 135 ft long.
- Surface area
- 363 ac
- Normal storage
- 3,269 ac-ft
- Max storage
- 3,670 ac-ft
- Drainage area
- 56 sq mi
- Hazard class
- Low
- Owner
- MNDNR-Wildlife
Source: USACE National Inventory of Dams, NID ID MN00401 · Operator website
EPA Impairment Status
Ann 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 MN33-0040-00 · 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: 2024-08-18
Monitoring stations: 3