Big Swan Lake
Big Swan Lake in Todd County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9 ft visibility. Maximum depth: 45 ft. Surface area: 946.56 acres.
- Clarity
- 9 ft
- Typical in August
- 71°F
- Max depth
- 45 ft
- Area
- 947 acres
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 13
- Open water
- 230 days
Next lake in Todd County
Free interactive depth-contour map of Big Swan Lake, reaching a maximum surveyed depth of 45 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Why Big Swan Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Big Swan Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Big Swan Lake is a 947-acre lake in Todd County, Minnesota with a maximum depth of 45 feet (18-foot average). Overall water quality is improving over recent sampling years. The lake supports 16 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-16. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Big Swan Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 9 ft. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Big Swan Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Swan Lake in Todd 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 Swan Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Big Swan Lake typically sits around 71°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 75°F) and coldest in Oct (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 33 field readings (2023–2025) via the EPA Water Quality Portal. See the full Big Swan Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Swan Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (194,089 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 | 45 ft |
| Average Depth | 18 ft |
| Surface Area | 947 acres |
| Shoreline Length | 7.8 mi |
| Littoral Zone | 43% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Big Swan LakePublic
- Lady LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big Swan Lake
DNR Fisheries Survey Summary
20 surveys on file from MN DNR Fisheries. Most recent: 2025-07-14 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 25.06 | 0.16 lb |
| PGS | 16.69 | — |
| BNS | 8.36 | — |
| Bluntnose Minnow | 8.30 | — |
| Northern Pike | 8.24 | 2.18 lb |
| Largemouth Bass | 7.83 | 1.47 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
Northern Pike
Largemouth Bass
From the 2025-07-14 survey
A targeted survey of nearshore fish species in Big Swan Lake was conducted on July 14- 16, 2025, by Lake Biological Monitoring and Assessment Program (LBMA) 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…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Swan 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 SwanFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Big Swan (1060)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Big SwanFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Big SwanPublic 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 | +0.154 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (70 observations).
Estimated open water season: 230 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-22 (2012) | 2013-05-11 (2013) |
| Ice-In | 2020-11-02 (2020) | 2015-12-22 (2015) |
Most recent ice-out: 2022-04-30
EPA Impairment Status
Big Swan 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 MN77-0023-00 · Official waterbody report
Graded lakes near Big Swan Lake
Big Swan Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Todd County
Frequently asked questions about Big Swan Lake
What is the water quality grade for Big Swan Lake?
- Big Swan Lake in Todd County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9 ft visibility. Maximum depth: 45 ft. Surface area: 946.56 acres.
Is Big Swan Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Big Swan Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Big Swan Lake?
- Big Swan Lake typically sits around 71°F at the surface in August, from 33 EPA Water Quality Portal field readings (2023–2025). That is a typical value for the month, not a live reading.
How deep is Big Swan Lake?
- Big Swan Lake has a maximum depth of 45 feet and an average depth of 18 feet. The lake covers 946.56 acres.
What fish are in Big Swan Lake?
- Fish species found in Big Swan Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow bullhead, yellow perch. Big Swan Lake is located in Todd County, Minnesota.
When does Big Swan Lake thaw?
- Big Swan Lake typically has ice-out around Apr 13. Ice typically forms around Nov 29. The open water season is approximately 230 days.
Does Big Swan Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Swan Lake (clouds, ice, or an off-season gap). The most recent reading was high (194,089 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 Swan Lake?
- Big Swan Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Big Swan Lake, Lady Lake. Public access is listed as yes.
Explore Big Swan Lake across LakeGrade
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Species activity outlook by water temperature and season
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Where this data comes from
211 measurements from 3 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
MNPCA211 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (3)
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