South Farm Lake
Lake County, Minnesota564 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for South Farm Lake. Here is what has been measured.
- Impaired · Mercury
- 31 ft max depth
- Limited data
South Farm Lake in Lake County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5 ft visibility. Maximum depth: 31 ft. Surface area: 563.98 acres.
Minnesota DNR's Standard Survey on July 17, 2023 caught 5.00 walleye per gill net at South Farm Lake. Length samples in the latest survey that recorded them ran 8–24 inches. DNR survey details →
South Farm Lake is a 564-acre lake in Lake County, Minnesota with a maximum depth of 31 feet. Water clarity is declining over recent sampling years. The lake supports 11 documented fish species including black crappie, bluegill, and burbot. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Methodology: how these readings are compared.
What South Farm Lake is good for
From access and monitoring records, not editorial picks.
- Fishing11 species recorded
- Deep water31 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. South Farm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether South Farm 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 South Farm Lake
These are the measurements Minnesota PCA publishes for South Farm 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 5 ft. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5ft | 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. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about South Farm Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
South Farm Lake typically sits around 67°F at the surface in September. Summer average is about 66°F. Usually warmest in Aug (about 68°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (55°F) to its warmest (68°F).
Typical surface water temperature by month, from 69 field readings (2023–2025) via the EPA Water Quality Portal. See the full South Farm Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for South Farm Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (731,139 cells/mL) on May 30, 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 17, 2023 caught 5.00 walleye per gill net at South Farm Lake. Length samples in the latest survey that recorded them ran 8–24 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows South Farm Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2025-07-31 (Targeted Survey).
13 surveys on file · most recent 2025-07-31 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Tullibee (Cisco) | 14.63 | 6–13 in 2023-07-17 | 0.38 lb |
| Bluegill | 5.25 | 3–9 in 2023-07-17 | 0.21 lb |
| Yellow Perch | 4.04 | 5–11 in 2023-07-17 | 0.16 lb |
| White Sucker | 2.66 | 6–20 in 2023-07-17 | 2.22 lb |
| Walleye | 2.24 | 8–24 in 2023-07-17 | 1.19 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.
Tullibee (Cisco)
Bluegill
Yellow Perch
White Sucker
From the 2025-07-31 survey
Temperature and dissolved oxygen measurements were collected from the deepest basin in South Farm Lake on July 31st, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for South Farm Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — South FarmFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — South FarmFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
31 ft
Surface area
564 acres
Shoreline
10.8 mi
Littoral zone
64%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Stays via Stay22
Stays near South Farm Lake
Compare lakeside cabins, hotels, and vacation rentals near South Farm Lake in Lake 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 South Farm 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 South Farm Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing South Farm Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Stable+0.19 µg/L/yr6 years
Chlorophyll-a
Improving-0.15 µg/L/yr6 years
EPA Impairment Status
South Farm Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MN38-0778-00 · Official waterbody report
Nearby Lakes in Lake County
Frequently asked questions about South Farm Lake
Where is South Farm Lake?
- South Farm Lake is a lake in Lake County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of South Farm Lake?
- South Farm Lake in Lake County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5 ft visibility. Maximum depth: 31 ft. Surface area: 563.98 acres.
Is South Farm Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. South Farm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
What is the water temperature of South Farm Lake?
- South Farm Lake typically sits around 67°F at the surface in September, from 69 EPA Water Quality Portal field readings (2023–2025). That is a typical value for the month, not a live reading.
How deep is South Farm Lake?
- South Farm Lake has a maximum depth of 31 feet. The lake covers 563.98 acres.
What fish are in South Farm Lake?
- Fish species found in South Farm Lake include black crappie, bluegill, burbot, cisco species, northern pike, rock bass, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow perch. South Farm Lake is located in Lake County, Minnesota.
What did the DNR fisheries survey find at South Farm Lake?
- Minnesota DNR's Standard Survey on July 17, 2023 caught 5.00 walleye per gill net at South Farm Lake. Length samples in the latest survey that recorded them ran 8–24 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows South Farm Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Does South Farm Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for South Farm Lake (clouds, ice, or an off-season gap). The most recent reading was high (731,139 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Can I fish at South Farm Lake?
- Public access to South Farm Lake is listed as no on the lake record, so confirm before you make the trip. 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 South Farm Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Lake County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near South Farm Lake
Other Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
85 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
MNPCA85 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
Impairment status from EPA ATTAINS 303(d) database
Lake details from Minnesota DNR LakeFinder