Ann Lake
Kanabec County, Minnesota653 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Ann Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- 17 ft max depth
- Public access
Ann Lake in Kanabec County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 73.5 µg/L. Chlorophyll-a (algae): 57 µg/L. Maximum depth: 17 ft. Surface area: 653.49 acres.
Minnesota DNR's Targeted Survey on June 21, 2021 caught 1.89 walleye per gill net at Ann Lake. DNR survey details →
Ann Lake is a 653-acre productive, nutrient-rich eutrophic lake in Kanabec County, Minnesota with a maximum depth of 17 feet. Overall water quality is declining over recent sampling years. The lake supports 13 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Kanabec County, Ann Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-27. Methodology: how these readings are compared.
Ann Lake covers about 650 acres in Kanabec County. It has one public boat landing. The median ice-out date is April 16, which is when the open-water season begins. If you are planning to stay, you can search lake houses and cabins around Ann Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Ann Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing13 species recorded
- Ice seasonIce-out around Apr 16
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Ann Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Ann Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Ann Lake
These are the measurements Minnesota PCA publishes for Ann Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2 ft of visibility. Phosphorus 73.5 µg/L. Chlorophyll-a 57 µg/L. TSI 68.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 73.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 57µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 68 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Ann Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Ann Lake typically sits around 61°F at the surface in October. Summer average is about 74°F. Usually warmest in Jul (about 75°F) and coldest in May (about 60°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (60°F) to its warmest (75°F).
Typical surface water temperature by month, from 63 field readings (2018–2025) via the EPA Water Quality Portal. See the full Ann Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Ann Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (816,582 cells/mL) on July 9, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Targeted Survey on June 21, 2021 caught 1.89 walleye per gill net at Ann Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Ann Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2021-06-21 (Targeted Survey).
10 surveys on file · most recent 2021-06-21 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Perch | 10.81 | 3–9 in 2021-06-21 | 0.14 lb |
| Largemouth Bass | 9.96 | 5–16 in 2021-06-21 | 1.44 lb |
| Bluegill | 6.66 | 3–9 in 2021-06-21 | 0.3 lb |
| Black Crappie | 4.83 | 4–11 in 2021-06-21 | 0.32 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and 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.
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.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —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
Lake Details
Max depth
17 ft
Surface area
653 acres
Shoreline
11.4 mi
Littoral zone
92%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
59 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,030 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Ann LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Ann Lake
Compare lakeside cabins, hotels, and vacation rentals near Ann Lake in Kanabec 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Ann Lake are listed below.
Top-rated places to stay near Ann Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fish Species
Click a species to see every lake where it is documented.
Fishing Ann Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving3 years
Phosphorus
Worsening+3.31 µg/L/yr6 years
Chlorophyll-a
Worsening+5.25 µg/L/yr6 years
Ice season
Typical ice-out
Apr 16
Earliest Mar 25, 2000 · Latest May 16, 2013
Typical ice-in
Nov 21
Earliest Nov 8, 2003 · Latest Dec 15, 1999
Most recent ice-out
Apr 22
2019
83 observations · Minnesota PCA ice records
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
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN33-0040-00 · Official waterbody report
Nearby Lakes in Kanabec County
Frequently asked questions about Ann Lake
Where is Ann Lake?
- Ann Lake is a lake in Kanabec County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Ann Lake?
- Ann Lake in Kanabec County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 73.5 µg/L. Chlorophyll-a (algae): 57 µg/L. Maximum depth: 17 ft. Surface area: 653.49 acres.
Is Ann Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Ann Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Ann Lake?
- Ann Lake typically sits around 61°F at the surface in October, from 63 EPA Water Quality Portal field readings (2018–2025). That is a typical value for the month, not a live reading.
How deep is Ann Lake?
- Ann Lake has a maximum depth of 17 feet. The lake covers 653.49 acres.
What fish are in Ann Lake?
- Fish species found in Ann Lake include black crappie, bluegill, bowfin (dogfish), channel catfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, shorthead redhorse, walleye, white sucker, yellow bullhead, yellow perch. Ann Lake is located in Kanabec County, Minnesota.
What did the DNR fisheries survey find at Ann Lake?
- Minnesota DNR's Targeted Survey on June 21, 2021 caught 1.89 walleye per gill net at Ann Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Ann Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Ann Lake thaw?
- Ann Lake typically has ice-out around Apr 16. Ice typically forms around Nov 21. The open water season is approximately 219 days.
Does Ann Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Ann Lake (clouds, ice, or an off-season gap). The most recent reading was high (816,582 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Ann Lake?
- Ann Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Ann Lake. Public access is listed as yes.
Can I fish at Ann Lake?
- Ann Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
95 measurements from 4 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
MNPCA95 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (4)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate