Ann Lake
Ann Lake in Pope County, Minnesota has a water quality grade of D (Nutrient-rich). 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.
- Clarity
- 7.2 ft
- Max depth
- 14 ft
- Area
- 370 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Ann Lake →
Next lake in Pope County
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). Water quality is graded D based on 2 sampling years through 2025. 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 2 public boat landings. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Moderate clarity, visible to about 7.2 ft. Phosphorus level: 496.5 µg/L. Chlorophyll-a: 17.6 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | Not graded |
| Phosphorus | 496.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 17.6 µg/L | Poor |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay 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 grade measures nutrients and algae, not lodging — cabins and rentals around Ann Lake are listed below.
Top-rated places to stay near Ann Lake
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 →
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 ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 14 ft |
| Average Depth | 12 ft |
| Surface Area | 370 acres |
| Shoreline Length | 3.4 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake Reno (Southeast)Public
- Ann LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Ann Lake
DNR Fisheries Survey Summary
8 surveys on file from MN DNR Fisheries. Most recent: 2023-04-27 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 169.12 | 0.37 lb |
| Common Carp | 137.39 | 3.89 lb |
| Black Crappie | 59.59 | 0.15 lb |
| Yellow Perch | 57.23 | 0.27 lb |
| Largemouth Bass | 18.05 | 0.53 lb |
| GOS | 12.22 | 0.06 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
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
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.005 m/yr | 6 |
| Phosphorus | → Stable | +7.94 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +3.36 µg/L/yr | 6 |
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 MN61-0122-00 · Official waterbody report
County Ranking
Ranked #15 of 20 lakes in Pope County
Nearby Lakes With Higher Grades
Ann Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Pope County
Frequently asked questions about Ann Lake
What is the water quality grade for Ann Lake?
- Ann Lake in Pope County, Minnesota has a water quality grade of D (Nutrient-rich). 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?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Ann Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 17.6 µg/L. Always check local health department advisories before swimming.
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.
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 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lake Reno (Southeast), Ann Lake. Public access is listed as yes.
Explore Ann Lake across LakeGrade
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Species activity outlook by water temperature and season
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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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated 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