South Sturgeon Lake
South Sturgeon Lake in St. Louis County, Minnesota has a water quality grade of A (Excellent). Water clarity: 2.5 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 5.9 µg/L. Maximum depth: 43 ft. Surface area: 204.44 acres.
- Clarity
- 2.5 ft
- Typical in August
- 56°F
- Max depth
- 43 ft
- Area
- 204 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 21
- Open water
- 211 days
Next lake in St. Louis County
South Sturgeon Lake is a 204-acre productive, nutrient-rich eutrophic lake in St. Louis County, Minnesota with a maximum depth of 43 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 10 documented fish species including black crappie, bluegill, and golden redhorse. Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in St. Louis County, South Sturgeon Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-07. 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)
Very murky, less than 2.5 ft of visibility. Phosphorus level: 20 µg/L. Chlorophyll-a: 5.9 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.5 ft | Not graded |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | 5.9 µg/L | Good |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near South Sturgeon Lake
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Water Temperature
South Sturgeon Lake typically sits around 56°F at the surface in August. Summer average is about 55°F. Usually warmest in Jul (about 56°F) and coldest in May (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 143 field readings (2017–2025) via the EPA Water Quality Portal. See the full South Sturgeon Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 43 ft |
| Surface Area | 204 acres |
| Shoreline Length | 3.7 mi |
| Littoral Zone | 22% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- South Sturgeon LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing South Sturgeon Lake
DNR Fisheries Survey Summary
8 surveys on file from MN DNR Fisheries. Most recent: 2016-07-18 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Tullibee (Cisco) | 8.97 | 0.66 lb |
| Bluegill | 5.11 | 0.21 lb |
| Black Crappie | 1.84 | 0.27 lb |
| Yellow Perch | 1.00 | 0.16 lb |
| Northern Pike | 0.71 | 2.67 lb |
| SLR | 0.63 | 3.68 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.
Tullibee (Cisco)
Bluegill
Black Crappie
Yellow Perch
From the 2016-07-18 survey
South Sturgeon Lake is a small, infertile lake located about 15 miles northwest of Chisholm, Minnesota. There is a public access on the southwest side of the lake. Small, accessible, infertile lakes like South Sturgeon often do not have the ability to produce high quality fisheries and are vulnerable to angling…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for South Sturgeon Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — South SturgeonFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — South Sturgeon (0831)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — South SturgeonPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.181 m/yr | 6 |
| Phosphorus | ↓ Declining | +4.5 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (42 observations).
Estimated open water season: 211 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2000-03-31 (2000) | 1996-05-10 (1996) |
| Ice-In | 2019-11-01 (2019) | 2011-11-30 (2011) |
Most recent ice-out: 2005-04-14
EPA Impairment Status
South Sturgeon 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 MN69-0939-03 · Official waterbody report · Matched by proximity (2.81 km)
County Ranking
Ranked #2 of 68 lakes in St. Louis County
Nearby Lakes in St. Louis County
Frequently asked questions about South Sturgeon Lake
What is the water quality grade for South Sturgeon Lake?
- South Sturgeon Lake in St. Louis County, Minnesota has a water quality grade of A (Excellent). Water clarity: 2.5 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 5.9 µg/L. Maximum depth: 43 ft. Surface area: 204.44 acres.
Is South Sturgeon Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. South Sturgeon Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 5.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of South Sturgeon Lake?
- South Sturgeon Lake typically sits around 56°F at the surface in August, from 143 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.
How deep is South Sturgeon Lake?
- South Sturgeon Lake has a maximum depth of 43 feet. The lake covers 204.44 acres.
What fish are in South Sturgeon Lake?
- Fish species found in South Sturgeon Lake include black crappie, bluegill, golden redhorse, northern pike, pumpkinseed, rock bass, shorthead redhorse, walleye, white sucker, yellow perch. South Sturgeon Lake is located in St. Louis County, Minnesota.
When does South Sturgeon Lake thaw?
- South Sturgeon Lake typically has ice-out around Apr 21. Ice typically forms around Nov 18. The open water season is approximately 211 days.
Are there boat ramps on South Sturgeon Lake?
- South Sturgeon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include South Sturgeon Lake. Public access is listed as yes.
Explore South Sturgeon Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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State Parks Near South Sturgeon Lake
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Where this data comes from
75 measurements from 2 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
MNPCA75 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Phosphorus by Colorimetry
- 2130 B ~ Nephelometric Method
- 2120 B ~ Color in Water by Visual Comparison
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
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