Big Sandy Lake
Aitkin County, Minnesota6,125 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Big Sandy Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- flowering rush
- 84 ft max depth
- Public access
Big Sandy Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 11 µg/L. Maximum depth: 84 ft. Surface area: 6124.86 acres.
Minnesota DNR's Targeted Survey on July 10, 2023 caught 6.13 walleye per gill net at Big Sandy Lake. Length samples in the latest survey that recorded them ran 3–18 inches. DNR survey details →
Free interactive depth-contour map of Big Sandy Lake, reaching a maximum surveyed depth of 80 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Big Sandy Lake is a 6,125-acre productive, nutrient-rich eutrophic lake in Aitkin County, Minnesota with a maximum depth of 84 feet (21-foot average). Overall water quality is improving over recent sampling years. The lake supports 22 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 4 public boat landings. Compared to the 17 other monitored lakes in Aitkin County, Big Sandy Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-20. Methodology: how these readings are compared.
At about 6,100 acres, Big Sandy Lake is large enough that where you stay decides which shore you see most of. It has 4 public boat landings, so a lakefront rental is not the only way to get a boat on the water. The median ice-out date is April 21, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Big Sandy Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Big Sandy Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Fishing22 species recorded
- Ice seasonIce-out around Apr 21
- Deep water84 ft surveyed max depth
- Big water6,125 acres
Swimming conditions
Readings onlyRecreation use not supported
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. Big Sandy Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Big Sandy 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 Big Sandy Lake
These are the measurements Minnesota PCA publishes for Big Sandy Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.5 ft. Phosphorus 30 µg/L. Chlorophyll-a 11 µg/L. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 30µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 11µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Big Sandy Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Big Sandy Lake typically sits around 61°F at the surface in October. Summer average is about 76°F. Usually warmest in Jul (about 77°F) and coldest in Oct (about 61°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (61°F) to its warmest (77°F).
Typical surface water temperature by month, from 96 field readings (2022–2025) via the EPA Water Quality Portal. See the full Big Sandy Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Sandy Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (554,626 cells/mL) on November 1, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Targeted Survey on July 10, 2023 caught 6.13 walleye per gill net at Big Sandy Lake. Length samples in the latest survey that recorded them ran 3–18 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Sandy Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
43 surveys on file from MN DNR Fisheries. Most recent: 2025-10-06 (Targeted Survey).
43 surveys on file · most recent 2025-10-06 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Walleye | 63.48 | 3–18 in 2025-10-06 | 0.66 lb |
| Yellow Perch | 21.10 | 5–11 in 2023-07-10 | 0.3 lb |
| Golden Shiner | 11.57 | ||
| Largemouth Bass | 8.67 | 8–18 in 2016-07-25 | 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.
Walleye
Yellow Perch
Largemouth Bass
From the 2025-10-06 survey
Fall night electrofishing (EW) was conducted on 10/02/2025 (representative locations) and 10/06/2025 (standard locations) to monitor natural reproduction, recruitment, and specifically the abundance of young-of-the-year (YOY) and yearling (age 1) Walleye. Eight standard locations have been sampled annually since 2009…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Sandy Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Big SandyFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Big Sandy (0119)Aquatic Plant Report · MN DNR LakeFinder
- —Aquatic Plant Report — Big Sandy (0152)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — Big SandyPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
84 ft
Average depth
21.4 ft
Surface area
6,125 acres
Shoreline
57 mi
Littoral zone
54%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Recreation & Access
- Big Sandy Lake (East)Public
- Big Sandy Lake (North)Public
- Big Sandy Lake (South Central)Public
- Dam SitePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Big Sandy Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Sandy Lake in Aitkin 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 Sandy Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 trip? Cabins and lodging at Big Sandy Lake → · more Minnesota lake trips
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Fish Species
Click a species to see every lake where it is documented.
Fishing Big Sandy 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 Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Improving-0.75 µg/L/yr5 years
Chlorophyll-a
Improving-0.49 µg/L/yr5 years
Ice season
Typical ice-out
Apr 21
Earliest Mar 16, 2024 · Latest May 12, 2013
Typical ice-in
Nov 30
Earliest Nov 13, 2002 · Latest Dec 23, 2001
Most recent ice-out
Apr 14
2025
143 observations · Minnesota PCA ice records
EPA Impairment Status
Big Sandy Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN01-0062-00 · Official waterbody report
Nearby Lakes in Aitkin County
Frequently asked questions about Big Sandy Lake
Where is Big Sandy Lake?
- Big Sandy Lake is a lake in Aitkin County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Big Sandy Lake?
- Big Sandy Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 11 µg/L. Maximum depth: 84 ft. Surface area: 6124.86 acres.
Is Big Sandy Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Big Sandy Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Big Sandy Lake?
- Big Sandy Lake typically sits around 61°F at the surface in October, from 96 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.
How deep is Big Sandy Lake?
- Big Sandy Lake has a maximum depth of 84 feet and an average depth of 21.4 feet. The lake covers 6124.86 acres.
What fish are in Big Sandy Lake?
- Fish species found in Big Sandy Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, burbot, channel catfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, redhorse, rock bass, shorthead redhorse, silver redhorse, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Big Sandy Lake is located in Aitkin County, Minnesota.
What did the DNR fisheries survey find at Big Sandy Lake?
- Minnesota DNR's Targeted Survey on July 10, 2023 caught 6.13 walleye per gill net at Big Sandy Lake. Length samples in the latest survey that recorded them ran 3–18 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Sandy Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Big Sandy Lake thaw?
- Big Sandy Lake typically has ice-out around Apr 21. Ice typically forms around Nov 30. The open water season is approximately 223 days.
Does Big Sandy Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Sandy Lake (clouds, ice, or an off-season gap). The most recent reading was high (554,626 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 Sandy Lake?
- Big Sandy Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Big Sandy Lake (East), Big Sandy Lake (North), Big Sandy Lake (South Central), Dam Site. Public access is listed as yes.
Can I fish at Big Sandy Lake?
- Big Sandy Lake has 4 documented boat landings 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 Big Sandy Lake across LakeQuality
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Where this data comes from
597 measurements from 15 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
MNPCA597 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (15)
- MNPCA-01-0062-00-220
- MNPCA-01-0062-00-223
- MNPCA-01-0062-00-226
- MNPCA-01-0062-00-207
- MNPCA-01-0062-00-206
- MNPCA-01-0062-00-205
- MNPCA-01-0062-00-221
- MNPCA-01-0062-00-208
- MNPCA-01-0062-00-203
- MNPCA-01-0062-00-213
- MNPCA-01-0062-00-217
- MNPCA-01-0062-00-218
- MNPCA-01-0062-00-212
- MNPCA-01-0062-00-222
- MNPCA-01-0062-00-102
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
Impairment status from EPA ATTAINS 303(d) database
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate