Ann Lake
Sherburne County, Minnesota183 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Ann Lake. Here is what has been measured.
- Mesotrophic
- zebra mussel
- 26 ft max depth
- Public access
- Limited data
Ann Lake in Sherburne County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 11.5 ft visibility. Phosphorus: 15.5 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Maximum depth: 26 ft. Surface area: 182.85 acres.
Minnesota DNR's Standard Survey on July 15, 2019 caught 17.50 northern pike per gill net at Ann Lake. Length samples in the latest survey that recorded them ran 8–36 inches. DNR survey details →
Ann Lake is a 183-acre mesotrophic lake in Sherburne County, Minnesota with a maximum depth of 26 feet (8-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 17 other monitored lakes in Sherburne County, Ann Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-11-14. Methodology: how these readings are compared.
What Ann Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11.5 ft of visibility
- Boat launch1 documented ramp
- Fishing10 species recorded
- Ice seasonIce-out around Mar 24
Swimming conditions
Readings onlyLimited data
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. 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.
Good clarity, visible to about 11.5 ft. Phosphorus 15.5 µg/L. Chlorophyll-a 4.3 µg/L. TSI 44.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 11.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 15.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 4.3µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 44 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Ann Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on July 15, 2019 caught 17.50 northern pike per gill net at Ann Lake. Length samples in the latest survey that recorded them ran 8–36 inches.
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 3 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 2019-07-15 (Standard Survey).
6 surveys on file · most recent 2019-07-15 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 65.14 | 2–7 in 2019-07-15 | 0.1 lb |
| Yellow Bullhead | 43.62 | 5–14 in 2019-07-15 | 0.44 lb |
| Pumpkinseed | 7.20 | 3–9 in 2019-07-15 | 0.16 lb |
| Northern Pike | 6.80 | 8–36 in 2019-07-15 | 2.39 lb |
| Largemouth Bass | 5.72 | 6–20 in 2019-07-15 | 1.65 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.
Bluegill
Yellow Bullhead
Pumpkinseed
Northern Pike
From the 2019-07-15 survey
Ann Lake is located in Sherburne County, five miles west of Zimmerman. The lake is 184 acres with a maximum depth of 26 feet. The watershed is small and is dominated by forest and the lake is lightly developed. The lake has excellent water quality and a diverse aquatic plant community. A public access is located on…
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
- —Aquatic Plant Report — Ann (1369)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — AnnPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
26 ft
Average depth
7.9 ft
Surface area
183 acres
Shoreline
4.6 mi
Littoral zone
75%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Elevation
948 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 Sherburne 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.
Top-rated places to stay near Ann Lake
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Follow Ann Lake’s readings
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Fish Species
Click a species to see every 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.
Water quality readings over time
3 seasons of samples on record (2021–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening3 years
Ice season
Typical ice-out
Mar 24
Earliest Mar 4, 2024 · Latest Apr 11, 2022
Most recent ice-out
Mar 4
2024
3 observations · Minnesota PCA ice records
Nearby Lakes in Sherburne County
Frequently asked questions about Ann Lake
Where is Ann Lake?
- Ann Lake is a lake in Sherburne 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 Sherburne County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 11.5 ft visibility. Phosphorus: 15.5 µg/L. Chlorophyll-a (algae): 4.3 µg/L. Maximum depth: 26 ft. Surface area: 182.85 acres.
Is Ann Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Ann Lake?
- Ann Lake has a maximum depth of 26 feet and an average depth of 7.9 feet. The lake covers 182.85 acres.
What fish are in Ann Lake?
- Fish species found in Ann Lake include black bullhead, black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, yellow bullhead, yellow perch. Ann Lake is located in Sherburne County, Minnesota.
What did the DNR fisheries survey find at Ann Lake?
- Minnesota DNR's Standard Survey on July 15, 2019 caught 17.50 northern pike per gill net at Ann Lake. Length samples in the latest survey that recorded them ran 8–36 inches. 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 3 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 Mar 24.
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
15 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA15 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by 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
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