Swift Lake
Swift Lake in Cass County, Minnesota has a water quality grade of A (Excellent). Water clarity: 8.5 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 4.9 µg/L. Maximum depth: 52 ft. Surface area: 356.59 acres.
- Clarity
- 8.5 ft
- Typical in August
- 66°F
- Max depth
- 52 ft
- Area
- 357 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- No
Next lake in Cass County
Swift Lake is a 357-acre mesotrophic lake in Cass County, Minnesota with a maximum depth of 52 feet (14-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 13 documented fish species including black crappie, bluegill, and bowfin (dogfish). No public access — the lake is private or restricted. Compared to the 103 other monitored lakes in Cass County, Swift Lake ranks #63 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-29. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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)
Moderate clarity, visible to about 8.5 ft. Phosphorus level: 13 µg/L. Chlorophyll-a: 4.9 µg/L. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.5 ft | Not graded |
| Phosphorus | 13 µg/L | Good |
| Chlorophyll-a (Algae) | 4.9 µg/L | Good |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Swift Lake
Compare lakeside cabins, hotels, and vacation rentals near Swift Lake in Cass 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
Swift Lake typically sits around 66°F at the surface in August. Summer average is about 65°F. Usually warmest in Jul (about 66°F) and coldest in May (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 534 field readings (2011–2025) via the EPA Water Quality Portal. See the full Swift Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 52 ft |
| Average Depth | 14 ft |
| Surface Area | 357 acres |
| Shoreline Length | 5.6 mi |
| Littoral Zone | 52% |
| Public Access | No |
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 Swift Lake
DNR Fisheries Survey Summary
5 surveys on file from MN DNR Fisheries. Most recent: 2025-06-09 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 3.59 | 0.16 lb |
| Bluegill | 2.85 | 0.33 lb |
| Northern Pike | 2.56 | 1.65 lb |
| Black Bullhead | 2.13 | 0.73 lb |
| Tullibee (Cisco) | 1.85 | 1.93 lb |
| Pumpkinseed | 1.71 | 0.29 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.
Yellow Perch
Bluegill
Northern Pike
Black Bullhead
From the 2025-06-09 survey
Swift Lake is a 357-acre lake with 6 miles of shoreline and a maximum depth of 52 feet located north of Longville, MN. The DNR has classified Minnesota's lakes into 43 different classes based on physical, chemical and other characteristics. Swift Lake is in Lake Class 25; lakes in this class are generally deep, clear…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Swift Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — SwiftFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Swift (1651)Aquatic Plant Report · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.147 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.07 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -1.33 µg/L/yr | 6 |
County Ranking
Ranked #63 of 104 lakes in Cass County
Nearby Lakes in Cass County
Frequently asked questions about Swift Lake
What is the water quality grade for Swift Lake?
- Swift Lake in Cass County, Minnesota has a water quality grade of A (Excellent). Water clarity: 8.5 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 4.9 µg/L. Maximum depth: 52 ft. Surface area: 356.59 acres.
Is Swift Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Swift Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Swift Lake?
- Swift Lake typically sits around 66°F at the surface in August, from 534 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Swift Lake?
- Swift Lake has a maximum depth of 52 feet and an average depth of 14 feet. The lake covers 356.59 acres.
What fish are in Swift Lake?
- Fish species found in Swift Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow bullhead, yellow perch. Swift Lake is located in Cass County, Minnesota.
Explore Swift Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
78 measurements from 2 monitoring stations, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Leech Lake Band of Ojibwe
LEECHLAK_WQX70 samples · 2021 - Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA8 samples · 2024–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Standard Test Method for Sulfate Ion in Water
- Field measurement/observation, generic method
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder