Swan Lake
Swan Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.1 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 4 µg/L. Maximum depth: 44 ft. Surface area: 748.9 acres.
- Clarity
- 12.1 ft
- Typical in August
- 75°F
- Max depth
- 44 ft
- Area
- 749 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 18
- Open water
- 226 days
Next lake in Otter Tail County
Swan Lake is a 749-acre mesotrophic lake in Otter Tail County, Minnesota with a maximum depth of 44 feet (13-foot average). Water quality is graded A based on 2 sampling years through 2025. Water clarity 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. Compared to the 65 other monitored lakes in Otter Tail County, Swan Lake ranks #22 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. 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 12.1 ft. Phosphorus level: 18 µg/L. Chlorophyll-a: 4 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.1 ft | Not graded |
| Phosphorus | 18 µg/L | Good |
| Chlorophyll-a (Algae) | 4 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Swan Lake
Compare lakeside cabins, hotels, and vacation rentals near Swan Lake in Otter Tail 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
Swan Lake typically sits around 75°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 77°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 35 field readings (2011–2025) via the EPA Water Quality Portal. See the full Swan Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Swan Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was low (11,588 cells/mL) on November 8, 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 | 44 ft |
| Average Depth | 13 ft |
| Surface Area | 749 acres |
| Shoreline Length | 9.2 mi |
| Littoral Zone | 50% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- LyePublic
- Swan LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Swan 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
9 surveys on file from MN DNR Fisheries. Most recent: 2022-07-05 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Largemouth Bass | 29.21 | 1.04 lb |
| Bluegill | 29.08 | 0.1 lb |
| Green Sunfish | 19.60 | 0.05 lb |
| PGS | 15.65 | — |
| BCS | 9.11 | — |
| Yellow Bass | 7.31 | 0.68 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
Green Sunfish
Yellow Bass
From the 2022-07-05 survey
Swan Lake is a 689-acre mesotrophic (moderately fertile) lake located in southwestern Otter Tail County approximately three miles southeast of Fergus Falls, MN. Swan Lake is part of the Pomme de Terre River Watershed. The Pomme de Terre River outlet is located along the south shoreline of the lake and is unnavigable.…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Swan Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — SwanFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — SwanFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — SwanPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.347 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.59 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | +0.05 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (24 observations).
Estimated open water season: 226 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-11 (2024) | 2013-05-09 (2013) |
| Ice-In | 2018-11-12 (2018) | 2016-12-10 (2016) |
Most recent ice-out: 2024-03-11
EPA Impairment Status
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 MN56-0781-00 · Official waterbody report
County Ranking
Ranked #22 of 66 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
Frequently asked questions about Swan Lake
What is the water quality grade for Swan Lake?
- Swan Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.1 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 4 µg/L. Maximum depth: 44 ft. Surface area: 748.9 acres.
Is Swan Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Swan Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Swan Lake?
- Swan Lake typically sits around 75°F at the surface in August, from 35 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Swan Lake?
- Swan Lake has a maximum depth of 44 feet and an average depth of 13 feet. The lake covers 748.9 acres.
What fish are in Swan Lake?
- Fish species found in 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. Swan Lake is located in Otter Tail County, Minnesota.
When does Swan Lake thaw?
- Swan Lake typically has ice-out around Apr 18. Ice typically forms around Nov 30. The open water season is approximately 226 days.
Does Swan Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Swan Lake (clouds, ice, or an off-season gap). The most recent reading was low (11,588 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Swan Lake?
- Swan Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lye, Swan Lake. Public access is listed as yes.
Explore Swan Lake across LakeGrade
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Where this data comes from
133 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA133 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 (1)
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