Big Lake
Big Lake in Carlton County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10 ft visibility. Phosphorus: 13.5 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Maximum depth: 25 ft. Surface area: 526.42 acres.
- Clarity
- 10 ft
- Typical in August
- 72°F
- Max depth
- 25 ft
- Area
- 526 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 22
- Open water
- 211 days
Next lake in Carlton County
Big Lake is a 526-acre mesotrophic lake in Carlton County, Minnesota with a maximum depth of 25 feet (8-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 9 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 1 public boat landing. Compared to the 21 other monitored lakes in Carlton County, Big Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. 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 10 ft. Phosphorus level: 13.5 µg/L. Chlorophyll-a: 3.2 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | 13.5 µg/L | Good |
| Chlorophyll-a (Algae) | 3.2 µg/L | Good |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Big Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Lake in Carlton 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
Big Lake typically sits around 72°F at the surface in August. Summer average is about 70°F. Usually warmest in Jul (about 73°F) and coldest in Apr (about 46°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 268 field readings (2010–2025) 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 (293,765 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 | 25 ft |
| Average Depth | 8 ft |
| Surface Area | 526 acres |
| Shoreline Length | 8.1 mi |
| Littoral Zone | 84% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Big LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big Lake
DNR Fisheries Survey Summary
8 surveys on file from MN DNR Fisheries. Most recent: 2020-08-10 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Largemouth Bass | 19.53 | 0.99 lb |
| Bluegill | 10.06 | 0.12 lb |
| Northern Pike | 6.37 | 2.04 lb |
| Bluntnose Minnow | 5.77 | — |
| TPM | 4.89 | — |
| Yellow Perch | 3.98 | 0.12 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.
Largemouth Bass
Bluegill
Northern Pike
Yellow Perch
From the 2020-08-10 survey
Big Lake is a 526-acre lake located near Sawyer, Minnesota with 84% (440 acres) littoral area and a maximum depth of 25 feet. A DNR administered, concrete, back-in access is located off County Road #112. Largemouth Bass and Bluegill are the primary management species. Big was last surveyed in 2013. Big was surveyed…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Lake. 4 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
- —Aquatic Plant Report — Big (0255)Aquatic Plant Report · 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: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.11 m/yr | 6 |
| Phosphorus | ↓ Declining | +75.1 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.43 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (10 observations).
Estimated open water season: 211 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-13 (2024) | 2013-05-14 (2013) |
| Ice-In | 2003-11-06 (2003) | 2024-12-02 (2024) |
Most recent ice-out: 2025-04-14
EPA Impairment Status
Big Lake is officially listed as impaired under Clean Water Act §303(d) in the 2019 EPA reporting cycle.
Source: EPA ATTAINS assessment unit FDL_102 · Official waterbody report
County Ranking
Ranked #1 of 22 lakes in Carlton County
Nearby Lakes in Carlton County
Frequently asked questions about Big Lake
What is the water quality grade for Big Lake?
- Big Lake in Carlton County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10 ft visibility. Phosphorus: 13.5 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Maximum depth: 25 ft. Surface area: 526.42 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 3.2 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Big Lake?
- Big Lake typically sits around 72°F at the surface in August, from 268 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Big Lake?
- Big Lake has a maximum depth of 25 feet and an average depth of 8 feet. The lake covers 526.42 acres.
What fish are in Big Lake?
- Fish species found in Big Lake include black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, yellow perch. Big Lake is located in Carlton County, Minnesota.
When does Big Lake thaw?
- Big Lake typically has ice-out around Apr 22. Ice typically forms around Nov 19. The open water season is approximately 211 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 (293,765 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Big Lake?
- Big Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Lake. Public access is listed as yes.
Explore Big Lake across LakeGrade
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Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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Where this data comes from
374 measurements from 6 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Fond du Lac Band of Chippewa (MN)
FONDULAC_WQX339 samples · 2020–2024 - Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA35 samples · 2020–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
- 10200 H ~ Chlorophyll a-b-c Determination
- Color, APHA Platinum-Cobalt
- For determination of Copper by the Bicinchoninate method.
- Field measurement/observation, generic method
Monitoring station identifiers (6)
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