South Lake
Johnson County, Kansas5 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #10 of 13 in the county
South Lake in Johnson County, Kansas has a water quality grade of F (Algae-prone). Phosphorus: 177.2 µg/L. Chlorophyll-a (algae): 72 µg/L. Surface area: 5.2 acres.
- Area
- 5 acres
- Type
- Hypereutrophic
- Phosphorus
- 177.2 µg/L
- Chlorophyll-a
- 72 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near South Lake
Compare lakeside cabins, hotels, and vacation rentals near South Lake in Johnson County, Kansas — 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 Lake are listed below.
Top-rated places to stay near South Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Watch South Lake’s letter
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South Lake is a 5-acre highly nutrient-loaded hypereutrophic lake in Johnson County, Kansas. Water quality is graded F based on 3 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 12 other monitored lakes in Johnson County, South Lake ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2024-09-05. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
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.
The F is nutrients and algae, not a swimming clearance. South Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
No clarity data. Phosphorus 177.2 µg/L. Chlorophyll-a 72 µg/L. TSI 76. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 177.2 µg/L | Poor |
| Chlorophyll-a (Algae) | 72 µg/L | Poor |
| Trophic State Index (TSI) | 76 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 5 acres |
No bathymetric survey has been published for South Lake, so its depth is not documented here.
Fishing South Lake
Water Quality Trend: ↓ Declining
Based on 11 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +15.63 µg/L/yr | 11 |
| Chlorophyll-a | ↓ Declining | +2.58 µg/L/yr | 11 |
Reservoir Info (USACE NID)
South Lake is a man-made reservoir impounded by the South Lake Park Dam, built primarily for recreation on the Indian Creek-Tr; earth-type dam, 17 ft tall and 600 ft long.
- Surface area
- 5.2 ac
- Normal storage
- 17.3 ac-ft
- Max storage
- 66 ac-ft
- Drainage area
- 0.3 sq mi
- Hazard class
- High
- Owner
- OVERLAND PARK, CITY OF
Source: USACE National Inventory of Dams, NID ID KS07293 · Operator website · Matched by proximity (0.01 km)
EPA Impairment Status
South 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 KS-LM067501 · Official waterbody report · Matched by proximity (1.61 km)
County Ranking
Ranked #10 of 13 lakes in Johnson County
Nearby Lakes With Higher Grades
South Lake holds Grade F. 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 Johnson County
Frequently asked questions about South Lake
Where is South Lake?
- South Lake is a lake in Johnson County, Kansas. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for South Lake?
- South Lake in Johnson County, Kansas has a water quality grade of F (Algae-prone). Phosphorus: 177.2 µg/L. Chlorophyll-a (algae): 72 µg/L. Surface area: 5.2 acres.
Is South Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. South Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Explore South Lake across LakeQuality
More Kansas Lake Rankings
Other Grade F Lakes in Kansas
Hypereutrophic Lakes in Kansas
Where this data comes from
91 measurements from 1 monitoring station, 2012–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- EPA R7
EPA_R7_WQX91 samples · 2012–2024
Analytical methods
- Nutrient Analysis
- Total Phosphorus After Block Digestion
- Chlorophyll a
- Fluorometric Analysis of Chlorophyll a (originally 2334.22A)
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Total Nitrogen Calculation
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