Long Lake
Cass County, Minnesota246 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Long Lake. Here is what has been measured.
- 37 ft max depth
- Public access
- Limited data
Long Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 17 ft visibility. Maximum depth: 37 ft. Surface area: 246.3 acres.
Minnesota DNR's Targeted Survey on June 24, 2024 caught 0.56 northern pike per trap net at Long Lake. Length samples in the latest survey that recorded them ran 13–20 inches. DNR survey details →
Long Lake is a 246-acre lake in Cass County, Minnesota with a maximum depth of 37 feet. Overall water quality is declining over recent sampling years. The lake supports 12 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-17. Methodology: how these readings are compared.
Long Lake covers about 250 acres in Cass County. For a place on the water, look through cabin and lake-house rentals near Long Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Long Lake is good for
From access and monitoring records, not editorial picks.
- Clear water17 ft of visibility
- Fishing12 species recorded
- Deep water37 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Long 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 Long Lake
These are the measurements Minnesota PCA publishes for Long Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 17 ft down. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 17ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Long Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Long Lake typically sits around 76°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 80°F) and coldest in Jun (about 70°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (70°F) to its warmest (80°F).
Typical surface water temperature by month, from 15 field readings (2010–2025) via the EPA Water Quality Portal. See the full Long Lake water temperature breakdown →
Minnesota DNR's Targeted Survey on June 24, 2024 caught 0.56 northern pike per trap net at Long Lake. Length samples in the latest survey that recorded them ran 13–20 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Long Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2024-06-24 (Targeted Survey).
7 surveys on file · most recent 2024-06-24 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 22.61 | 3–9 in 2024-06-24 | 0.16 lb |
| Bluntnose Minnow | 17.47 | ||
| Largemouth Bass | 9.39 | 10–14 in 2024-06-24 | 0.86 lb |
| Black Crappie | 6.04 | 7–10 in 2024-06-24 | 0.37 lb |
| Northern Pike | 4.56 | 13–20 in 2024-06-24 | 1.61 lb |
| Yellow Bullhead | 4.40 | 7–11 in 2024-06-24 | 0.56 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.
Bluegill
Largemouth Bass
Black Crappie
Northern Pike
From the 2024-06-24 survey
A targeted survey of nearshore fish species in Long Lake was conducted on June 25-26, 2024 by Index of Biological Integrity (IBI) Program 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. Backpack electrofishing was…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LongFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Long (1611)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — LongPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
37 ft
Surface area
246 acres
Shoreline
5.1 mi
Littoral zone
57%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,332 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long 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.
Top-rated places to stay near Long 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 whole trip? See where to stay at Minnesota’s top lakes →
Follow Long Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Long Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Worsening+0.23 µg/L/yr6 years
Chlorophyll-a
Stable-0.01 µg/L/yr6 years
Nearby Lakes in Cass County
Frequently asked questions about Long Lake
Where is Long Lake?
- Long Lake is a lake in Cass County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Long Lake?
- Long Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 17 ft visibility. Maximum depth: 37 ft. Surface area: 246.3 acres.
Is Long Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Long Lake?
- Long Lake typically sits around 76°F at the surface in September, from 15 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Long Lake?
- Long Lake has a maximum depth of 37 feet. The lake covers 246.3 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, yellow bullhead, yellow perch. Long Lake is located in Cass County, Minnesota.
What did the DNR fisheries survey find at Long Lake?
- Minnesota DNR's Targeted Survey on June 24, 2024 caught 0.56 northern pike per trap net at Long Lake. Length samples in the latest survey that recorded them ran 13–20 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Long Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Long Lake?
- Public access to Long Lake is listed as yes on the lake record. 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.
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Where this data comes from
30 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
MNPCA30 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder