Shawnee Mission Lake
Johnson County, Kansas104 acresView mapDirections
KDHE publishes the water-quality measurements for Shawnee Mission Lake. Here is what has been measured.
- Limited data
Shawnee Mission Lake in Johnson County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 9.7 µg/L. Surface area: 103.8 acres.
Shawnee Mission Lake is a 104-acre lake in Johnson County, Kansas. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2015-08-12. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Shawnee Mission Lake is safe to swim in today is a call for the Kansas Department of Health and Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Shawnee Mission Lake
These are the measurements KDHE publishes for Shawnee Mission 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 4.3 ft. Phosphorus 20 µg/L. Chlorophyll-a 9.7 µg/L. TSI 52.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 9.7µg/L | Measured, not scored 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. | 52 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Shawnee Mission Lake
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Lake Details
Surface area
104 acres
No bathymetric survey has been published for Shawnee Mission Lake, so its depth is not documented here.
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Fishing Shawnee Mission Lake
Water quality readings over time
2 seasons of samples on record (2015–2017). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Worsening+1.35 µg/L/yr2 years
Chlorophyll-a
Improving-1.05 µg/L/yr2 years
Reservoir Info (USACE NID)
Shawnee Mission Lake is a man-made reservoir impounded by the Shawnee Mission Park Dam (completed 1958), built primarily for recreation on the Mill Creek-Tr; earth-type dam, 72 ft tall and 1,380 ft long.
- Surface area
- 103.8 ac
- Normal storage
- 2,423.2 ac-ft
- Max storage
- 3,500 ac-ft
- Drainage area
- 2.8 sq mi
- Hazard class
- High
- Owner
- JOHNSON COUNTY
Source: USACE National Inventory of Dams, NID ID KS02547 · Operator website · Matched by proximity (0.2 km)
Nearby Lakes in Johnson County
Frequently asked questions about Shawnee Mission Lake
Where is Shawnee Mission Lake?
- Shawnee Mission Lake is a lake in Johnson County, Kansas. Its water-quality measurements are published by KDHE and shown on this page as reported.
What is the water quality of Shawnee Mission Lake?
- Shawnee Mission Lake in Johnson County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 9.7 µg/L. Surface area: 103.8 acres.
Is Shawnee Mission Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Shawnee Mission Lake across LakeQuality
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Where this data comes from
5 measurements from 1 monitoring station, 2015. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX5 samples · 2015
Analytical methods
- Depth, Secchi disk depth
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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.