Ann Lake
Ann Lake in Carver County, Minnesota has a water quality grade of C (Fair). Water clarity: 8.7 ft visibility. Phosphorus: 29 µg/L. Chlorophyll-a (algae): 8.9 µg/L. Maximum depth: 45 ft. Surface area: 115.74 acres.
- Clarity
- 8.7 ft
- Typical in August
- 62°F
- Max depth
- 45 ft
- Area
- 116 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 11
Next lake in Carver County
Ann Lake is a 116-acre productive, nutrient-rich eutrophic lake in Carver County, Minnesota with a maximum depth of 45 feet. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 11 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 37 other monitored lakes in Carver County, Ann Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 8.7 ft. Phosphorus level: 29 µg/L. Chlorophyll-a: 8.9 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.7 ft | Not graded |
| Phosphorus | 29 µg/L | Fair |
| Chlorophyll-a (Algae) | 8.9 µg/L | Fair |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Ann Lake
Compare lakeside cabins, hotels, and vacation rentals near Ann Lake in Carver 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.
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Water Temperature
Ann Lake typically sits around 62°F at the surface in August. Summer average is about 60°F. Usually warmest in Aug (about 62°F) and coldest in Jan (about 38°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 936 field readings (2010–2025) via the EPA Water Quality Portal. See the full Ann Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 116 acres |
| Shoreline Length | 1.7 mi |
| Littoral Zone | 39% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake Ann, Lake Ann ParkPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Ann Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2023-08-16 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CNM | 53.49 | — |
| Bluegill | 45.03 | 0.16 lb |
| Bluntnose Minnow | 11.30 | — |
| Largemouth Bass | 6.77 | 1.46 lb |
| Black Bullhead | 5.74 | 0.51 lb |
| Green Sunfish | 4.83 | 0.08 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.
Bluegill
Largemouth Bass
Black Bullhead
Green Sunfish
From the 2023-08-16 survey
A targeted survey of nearshore fish species in Ann Lake was conducted on August 16-22, 2023, by Index of Biological Integrity (IBI) Program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Ann Lake. 2 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
- —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 | ↓ Declining | -0.257 m/yr | 6 |
| Phosphorus | ↓ Declining | +6.69 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +3.11 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (4 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2025-04-03 (2025) | 2022-04-11 (2022) |
| Ice-In | 2024-12-08 (2024) | 2022-12-18 (2022) |
Most recent ice-out: 2025-04-03
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 MN10-0012-00 · Official waterbody report
County Ranking
Ranked #8 of 38 lakes in Carver County
Nearby Lakes in Carver County
Frequently asked questions about Ann Lake
What is the water quality grade for Ann Lake?
- Ann Lake in Carver County, Minnesota has a water quality grade of C (Fair). Water clarity: 8.7 ft visibility. Phosphorus: 29 µg/L. Chlorophyll-a (algae): 8.9 µg/L. Maximum depth: 45 ft. Surface area: 115.74 acres.
Is Ann Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Ann Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 8.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Ann Lake?
- Ann Lake typically sits around 62°F at the surface in August, from 936 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Ann Lake?
- Ann Lake has a maximum depth of 45 feet. The lake covers 115.74 acres.
What fish are in Ann Lake?
- Fish species found in Ann Lake include black bullhead, black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, yellow bullhead, yellow perch. Ann Lake is located in Carver County, Minnesota.
When does Ann Lake thaw?
- Ann Lake typically has ice-out around Apr 11.
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 Lake Ann, Lake Ann Park. Public access is listed as yes.
Explore Ann Lake across LakeGrade
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Where this data comes from
284 measurements from 2 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
MNPCA284 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 (2)
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
Ice data from Minnesota DNR Climate