Ann Lake
Pope County, Minnesota370 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Ann Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 14 ft max depth
- Public access
Ann Lake in Pope County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.2 ft visibility. Phosphorus: 496.5 µg/L. Chlorophyll-a (algae): 17.6 µg/L. Maximum depth: 14 ft. Surface area: 369.77 acres.
Minnesota DNR's Targeted Survey on April 27, 2023 caught 4.00 walleye per trap net at Ann Lake. DNR survey details →
Ann Lake is a 370-acre productive, nutrient-rich eutrophic lake in Pope County, Minnesota with a maximum depth of 14 feet (12-foot average). Overall water quality is declining over recent sampling years. The lake supports 10 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 19 other monitored lakes in Pope County, Ann Lake ranks #15 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Methodology: how these readings are compared.
What Ann Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing10 species recorded
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 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.
Moderate clarity, visible to about 7.2 ft. Phosphorus 496.5 µg/L. Chlorophyll-a 17.6 µg/L. TSI 67.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 497µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 17.6µg/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. | 67 | 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.
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 (376,704 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 April 27, 2023 caught 4.00 walleye per trap 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
8 surveys on file from MN DNR Fisheries. Most recent: 2023-04-27 (Targeted Survey).
8 surveys on file · most recent 2023-04-27 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 169.12 | 5–11 in 2023-04-27 | 0.37 lb |
| Common Carp | 137.39 | 9–33 in 2023-04-27 | 3.89 lb |
| Black Crappie | 59.59 | 5–14 in 2023-04-27 | 0.15 lb |
| Yellow Perch | 57.23 | 6–12 in 2023-04-27 | 0.27 lb |
| Largemouth Bass | 18.05 | 7 in 2023-04-27 | 0.53 lb |
| Golden Shiner | 12.22 | 5–6 in 2010-08-30 | 0.06 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.
Black Bullhead
Common Carp
Black Crappie
Yellow Perch
From the 2023-04-27 survey
This targeted survey was completed to determine extent of winterkill following the severe 2022-2023 winter. Trap netting results suggested that winterkill severity was low and restorative stockings were not warranted. Gamefish species present included Black Crappie, Bluegill, Largemouth Bass, Walleye, and Yellow…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Ann Lake. 3 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
- —Fish Stocking History — AnnFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — AnnPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
14 ft
Average depth
12 ft
Surface area
370 acres
Shoreline
3.4 mi
Littoral zone
100%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
8 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,362 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 Pope 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
Stable6 years
Phosphorus
Stable+7.94 µg/L/yr6 years
Chlorophyll-a
Worsening+3.36 µg/L/yr6 years
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: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN61-0122-00 · Official waterbody report
Nearby Lakes in Pope County
Frequently asked questions about Ann Lake
Where is Ann Lake?
- Ann Lake is a lake in Pope 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 Pope County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.2 ft visibility. Phosphorus: 496.5 µg/L. Chlorophyll-a (algae): 17.6 µg/L. Maximum depth: 14 ft. Surface area: 369.77 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 nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Ann Lake?
- Ann Lake has a maximum depth of 14 feet and an average depth of 12 feet. The lake covers 369.77 acres.
What fish are in Ann Lake?
- Fish species found in Ann Lake include black bullhead, black crappie, bluegill, common carp, hybrid sunfish, largemouth bass, northern pike, walleye, white sucker, yellow perch. Ann Lake is located in Pope County, Minnesota.
What did the DNR fisheries survey find at Ann Lake?
- Minnesota DNR's Targeted Survey on April 27, 2023 caught 4.00 walleye per trap 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.
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 (376,704 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.
Explore Ann Lake across LakeQuality
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Where this data comes from
94 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA94 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 (1)
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