Upper South Long Lake
Crow Wing County, Minnesota804 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Upper South Long Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- 2 aquatic invasives
- 47 ft max depth
- Public access
Upper South Long Lake in Crow Wing County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 8.5 µg/L. Maximum depth: 47 ft. Surface area: 804.31 acres.
Minnesota DNR's Standard Survey on July 21, 2025 caught 2.33 walleye per gill net at Upper South Long Lake. Length samples in the latest survey that recorded them ran 8–28 inches. DNR survey details →
Free interactive depth-contour map of Upper South Long Lake, reaching a maximum surveyed depth of 45 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Upper South Long Lake is a 804-acre mesotrophic lake in Crow Wing County, Minnesota with a maximum depth of 47 feet. 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 1 public boat landing. Compared to the 84 other monitored lakes in Crow Wing County, Upper South Long Lake ranks #68 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Methodology: how these readings are compared.
Upper South Long Lake covers about 800 acres in Crow Wing County. It has one public boat landing. The median ice-out date is April 15, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Upper South Long Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Upper South Long Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing16 species recorded
- Ice seasonIce-out around Apr 15
- Deep water47 ft surveyed max depth
Swimming conditions
Readings onlyModerate algae
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. Upper South Long Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Upper South 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 Upper South Long Lake
These are the measurements Minnesota PCA publishes for Upper South Long 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 6 ft. Phosphorus 16 µg/L. Chlorophyll-a 8.5 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 16µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 8.5µg/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. | 49 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Upper South Long Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Upper South Long Lake typically sits around 61°F at the surface in September. Summer average is about 65°F. Usually warmest in Jul (about 65°F) and coldest in May (about 51°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (51°F) to its warmest (65°F).
Typical surface water temperature by month, from 48 field readings (2017–2025) via the EPA Water Quality Portal. See the full Upper South Long Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Upper South Long Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (94,624 cells/mL) on April 21, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Standard Survey on July 21, 2025 caught 2.33 walleye per gill net at Upper South Long Lake. Length samples in the latest survey that recorded them ran 8–28 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Upper South Long 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
11 surveys on file from MN DNR Fisheries. Most recent: 2025-07-21 (Standard Survey).
11 surveys on file · most recent 2025-07-21 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Largemouth Bass | 19.39 | 4–18 in 2025-07-21 | 0.92 lb |
| Bluegill | 18.35 | 2–8 in 2025-07-21 | 0.13 lb |
| Bluntnose Minnow | 10.90 | ||
| Walleye | 6.44 | 8–28 in 2025-07-21 | 1.7 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.
Largemouth Bass
Bluegill
Walleye
From the 2025-07-21 survey
Upper South Long is an 804 acre lake 10 miles southeast of the city of Brainerd in Crow Wing County. Walleye is the primary management species, with the lake being stocked every other year (odd years) with 283 pounds of fingerlings. When surplus Walleye fry are available, up to 300,000 may be stocked; this last…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Upper South Long Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Upper South LongFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Upper South Long (0205)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Upper South LongFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Upper South LongPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
47 ft
Surface area
804 acres
Shoreline
6.3 mi
Littoral zone
35%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
97 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,181 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Upper South Long LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Upper South Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Upper South Long Lake in Crow Wing 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 Upper South Long Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fish Species
Click a species to see every lake where it is documented.
Fishing Upper South Long Lake
- → Upper South Long Lake fishing: DNR survey catch rates, species & stocking
- → Upper South Long Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Upper South Long Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Upper South Long Lake? (mercury & PFAS guide)
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
Improving6 years
Phosphorus
Improving-0.97 µg/L/yr6 years
Chlorophyll-a
Improving-1.44 µg/L/yr6 years
Ice season
Typical ice-out
Apr 15
Earliest Mar 13, 2024 · Latest May 10, 2013
Typical ice-in
Dec 3
Earliest Apr 1, 2010 · Latest Dec 23, 1998
Most recent ice-out
Apr 12
2025
56 observations · Minnesota PCA ice records
EPA Impairment Status
Upper South Long 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.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN18-0096-00 · Official waterbody report
Nearby Lakes in Crow Wing County
Frequently asked questions about Upper South Long Lake
Where is Upper South Long Lake?
- Upper South Long Lake is a lake in Crow Wing County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Upper South Long Lake?
- Upper South Long Lake in Crow Wing County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 8.5 µg/L. Maximum depth: 47 ft. Surface area: 804.31 acres.
Is Upper South Long Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Upper South Long Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Upper South Long Lake?
- Upper South Long Lake typically sits around 61°F at the surface in September, from 48 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.
How deep is Upper South Long Lake?
- Upper South Long Lake has a maximum depth of 47 feet. The lake covers 804.31 acres.
What fish are in Upper South Long Lake?
- Fish species found in Upper South Long Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, greater redhorse, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Upper South Long Lake is located in Crow Wing County, Minnesota.
What did the DNR fisheries survey find at Upper South Long Lake?
- Minnesota DNR's Standard Survey on July 21, 2025 caught 2.33 walleye per gill net at Upper South Long Lake. Length samples in the latest survey that recorded them ran 8–28 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Upper South Long 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 Upper South Long Lake thaw?
- Upper South Long Lake typically has ice-out around Apr 15. Ice typically forms around Dec 3. The open water season is approximately 232 days.
Does Upper South Long Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Upper South Long Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (94,624 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Upper South Long Lake?
- Upper South Long Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Upper South Long Lake. Public access is listed as yes.
Can I fish at Upper South Long Lake?
- Upper South Long Lake has 1 documented boat landing 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 Upper South Long Lake across LakeQuality
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Where this data comes from
195 measurements from 7 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
MNPCA195 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 (7)
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 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