Ann Lake
Wright County, MinnesotaHypereutrophic
Ann Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota average. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake bottoms out at 19 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 375 acres, Ann Lake fits the Minnesota median for monitored lakes, with 3.6 miles of shoreline. Within Wright County's 64 graded lakes, Ann Lake ranks 46 — 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 16 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. 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 2024-09-15. 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
Murky, only visible to about 3.7 ft. Phosphorus level: 267 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.7 ft | D |
| Phosphorus | 267 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 18.5 ft |
| Average Depth | 10.1 ft |
| Surface Area | 375.4 acres |
| Shoreline Length | 3.6 mi |
| Littoral Zone | 79% |
| 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: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.332 m/yr | 5 |
| Phosphorus | ↓ Declining | +38.75 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (4 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2016-03-13 (2016) | 2008-04-23 (2008) |
| Ice-In | 2008-11-20 (2008) | 2008-11-20 (2008) |
Most recent ice-out: 2016-03-13
Location
County Ranking
Ranked #46 of 64 lakes in Wright County
Cleaner Lakes Within 30 Miles
Ann Lake holds Grade D. 4 nearby lakes hold higher grades.
- BMary LakeWright County · mi · Two grade letters higher (D → B)
- BWaverly LakeWright County · mi · Two grade letters higher (D → B)
- CBrooks LakeWright County · mi · Higher grade (D → C)
- DHoward LakeWright County · mi · Higher overall water quality score
Nearby Lakes in Wright County
More Minnesota Lake Rankings
State Parks Near Ann Lake
Other Grade D Lakes in Minnesota
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2025-09-24 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 86.19 | 0.32 lb |
| Bluegill | 18.36 | 0.17 lb |
| Yellow Perch | 17.95 | 0.19 lb |
| Green Sunfish | 16.80 | 0.05 lb |
| Black Crappie | 16.52 | 0.25 lb |
| Largemouth Bass | 12.27 | 0.79 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.
Black Bullhead
Bluegill
Yellow Perch
Green Sunfish
From the 2025-09-24 survey
Ann Lake is a popular fishing lake located three miles south of Howard Lake in southern Wright County. The 386-acre lake has a maximum depth of 18.5 feet and a ten-year average water clarity of 3.3 feet. There is one public access located on the west side. The Walleye fishery of Ann Lake has been managed by stocking…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Ann Lake. 3 reports on file.
- —Fisheries Lake Survey — AnnFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — AnnFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — AnnPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Ann Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN86-0190-00 · 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: 2024-09-15
Monitoring stations: 1