Big Lake
Big Lake in Sherburne County, Minnesota has a water quality grade of A (Excellent). Water clarity: 13.6 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 6.1 µg/L. Maximum depth: 48 ft. Surface area: 253.66 acres.
- Clarity
- 13.6 ft
- Typical in August
- 77°F
- Max depth
- 48 ft
- Area
- 254 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 7
- Open water
- 247 days
Next lake in Sherburne County
Big Lake is a 254-acre mesotrophic lake in Sherburne County, Minnesota with a maximum depth of 48 feet (18-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 14 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available. Compared to the 17 other monitored lakes in Sherburne County, Big Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-25. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 13.6 ft. Phosphorus level: 10.5 µg/L. Chlorophyll-a: 6.1 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.6 ft | Not graded |
| Phosphorus | 10.5 µg/L | Good |
| Chlorophyll-a (Algae) | 6.1 µg/L | Good |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Big Lake
Compare lakeside cabins, hotels, and vacation rentals near Big 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 Big Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Big Lake typically sits around 77°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 78°F) and coldest in May (about 60°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 64 field readings (2011–2025) via the EPA Water Quality Portal. See the full Big Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (164,437 cells/mL) on November 22, 2025.
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 | 48 ft |
| Average Depth | 17.7 ft |
| Surface Area | 254 acres |
| Shoreline Length | 2.4 mi |
| Littoral Zone | 43% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big 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
8 surveys on file from MN DNR Fisheries. Most recent: 2017-07-31 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| SFS | 76.15 | — |
| Bluntnose Minnow | 42.28 | — |
| Bluegill | 18.59 | 0.13 lb |
| Largemouth Bass | 13.51 | 0.65 lb |
| Green Sunfish | 11.19 | 0.07 lb |
| Black Bullhead | 9.17 | 0.77 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
Green Sunfish
Black Bullhead
From the 2017-07-31 survey
Big Lake is a 251 acre lake located in Sherburne County within the city limits of Big Lake. It is connected to Mitchell Lake via a navigable channel. Big Lake has a maximum depth of 48 feet and a small watershed primarily composed of development, open water, and row crops. A city owned public access is located at the…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — BigFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — BigFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — BigPublic 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 | ↑ Improving | +0.228 m/yr | 6 |
| Phosphorus | ↓ Declining | +3.5 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +1.7 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (23 observations).
Estimated open water season: 247 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-10 (2024) | 2013-05-03 (2013) |
| Ice-In | 2006-12-09 (2006) | 2015-12-27 (2015) |
Most recent ice-out: 2024-03-10
EPA Impairment Status
Big Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN71-0082-00 · Official waterbody report
County Ranking
Ranked #1 of 18 lakes in Sherburne County
Nearby Lakes in Sherburne County
Frequently asked questions about Big Lake
What is the water quality grade for Big Lake?
- Big Lake in Sherburne County, Minnesota has a water quality grade of A (Excellent). Water clarity: 13.6 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 6.1 µg/L. Maximum depth: 48 ft. Surface area: 253.66 acres.
Is Big Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Big Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 6.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Big Lake?
- Big Lake typically sits around 77°F at the surface in August, from 64 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Big Lake?
- Big Lake has a maximum depth of 48 feet and an average depth of 17.7 feet. The lake covers 253.66 acres.
What fish are in Big Lake?
- Fish species found in Big Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Big Lake is located in Sherburne County, Minnesota.
When does Big Lake thaw?
- Big Lake typically has ice-out around Apr 7. Ice typically forms around Dec 10. The open water season is approximately 247 days.
Does Big Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Lake (clouds, ice, or an off-season gap). The most recent reading was high (164,437 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Explore Big Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Sherburne County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Moderate nutrients, good water quality
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State Parks Near Big Lake
Other Grade A Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Where this data comes from
109 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
MNPCA109 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
Ice data from Minnesota DNR Climate