South Long Lake
South Long Lake in Ramsey County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3.9 ft visibility. Phosphorus: 46 µg/L. Chlorophyll-a (algae): 22.8 µg/L. Maximum depth: 30 ft. Surface area: 172.63 acres.
- Clarity
- 3.9 ft
- Typical in August
- 70°F
- Max depth
- 30 ft
- Area
- 173 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 10
- Open water
- 237 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near South Long Lake →
Next lake in Ramsey County
South Long Lake is a 173-acre productive, nutrient-rich eutrophic lake in Ramsey County, Minnesota with a maximum depth of 30 feet. Water quality is graded D based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 43 other monitored lakes in Ramsey County, South Long Lake ranks #26 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria C
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.
Based on E. coli testing, South Long Lake occasionally exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 6.5% of 92 samples across 3 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Minnesota’s current beach and health-department advisories before swimming.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 3.9 ft. Phosphorus level: 46 µg/L. Chlorophyll-a: 22.8 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | Not graded |
| Phosphorus | 46 µg/L | Poor |
| Chlorophyll-a (Algae) | 22.8 µg/L | Poor |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near South Long Lake
Compare lakeside cabins, hotels, and vacation rentals near South Long Lake in Ramsey 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around South Long Lake are listed below.
Top-rated places to stay near South Long Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
South Long Lake typically sits around 70°F at the surface in August. Summer average is about 67°F. Usually warmest in Aug (about 70°F) and coldest in Mar (about 39°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 785 field readings (2010–2025) via the EPA Water Quality Portal. See the full South Long Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 30 ft |
| Surface Area | 173 acres |
| Shoreline Length | 3.9 mi |
| Littoral Zone | 64% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Long LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing South Long Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2021-08-02 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 85.28 | 0.18 lb |
| Black Crappie | 7.86 | 0.23 lb |
| Common Carp | 7.14 | 2.2 lb |
| Bluegill | 5.92 | 0.24 lb |
| Yellow Bass | 4.46 | 0.45 lb |
| White Sucker | 2.27 | 1.27 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.
Black Bullhead
Black Crappie
Common Carp
Bluegill
From the 2021-08-02 survey
Long Lake is a eutrophic, 172-acre water body in Ramsey County assigned to lake class 30. It is comprised of two sub-basins lying north and south of each other with Rice Creek flowing through the northern basin. Rice Creek continues on to connect with the Mississippi River which results in some fish species in Long…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for South 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
- —Fish Stocking History — LongFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — LongPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.071 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.7 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.95 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (15 observations).
Estimated open water season: 237 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2007-03-27 (2007) | 2013-04-28 (2013) |
| Ice-In | 2008-11-25 (2008) | 2004-12-15 (2004) |
Most recent ice-out: 2014-04-18
EPA Impairment Status
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN62-0067-02 · Official waterbody report
County Ranking
Ranked #26 of 44 lakes in Ramsey County
Nearby Lakes With Higher Grades
South Long Lake holds Grade D. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Ramsey County
Frequently asked questions about South Long Lake
What is the water quality grade for South Long Lake?
- South Long Lake in Ramsey County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3.9 ft visibility. Phosphorus: 46 µg/L. Chlorophyll-a (algae): 22.8 µg/L. Maximum depth: 30 ft. Surface area: 172.63 acres.
Is South Long Lake safe to swim in?
- Based on E. coli testing, South Long Lake occasionally exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 6.5% of 92 samples across 3 seasons. That works out to a bacteria swim-safety grade of C — a historical summary of past testing, not a current reading. South Long Lake has a water quality grade of D (Nutrient-rich). Bacteria levels can spike quickly after heavy rain, so always check Minnesota's current beach and health-department advisories before you swim.
What is the water temperature of South Long Lake?
- South Long Lake typically sits around 70°F at the surface in August, from 785 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is South Long Lake?
- South Long Lake has a maximum depth of 30 feet. The lake covers 172.63 acres.
What fish are in South Long Lake?
- Fish species found in South Long Lake include black bullhead, black crappie, bluegill, channel catfish, common carp, freshwater drum, largemouth bass, northern pike, smallmouth buffalo, walleye, white sucker, yellow bullhead. South Long Lake is located in Ramsey County, Minnesota.
When does South Long Lake thaw?
- South Long Lake typically has ice-out around Apr 10. Ice typically forms around Dec 3. The open water season is approximately 237 days.
Are there boat ramps on South Long Lake?
- South Long Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Long Lake. Public access is listed as yes.
Explore South Long Lake across LakeGrade
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Where this data comes from
340 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
MNPCA340 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- Turbidity by Nephelometry
Monitoring station identifiers (1)
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