Shawnee Mission Lake
Johnson County, Kansas104 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Limited data
Shawnee Mission Lake in Johnson County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.3 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 9.7 µg/L. Surface area: 103.8 acres.
- Clarity
- 4.3 ft
- Area
- 104 acres
- Phosphorus
- 20 µg/L
- Chlorophyll-a
- 9.7 µg/L
- Trend
- ↓ Declining
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Watch Shawnee Mission Lake’s letter
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Why Shawnee Mission Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Shawnee Mission Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by KDHE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Shawnee Mission Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 4.3 ft. Phosphorus 20 µg/L. Chlorophyll-a 9.7 µg/L. TSI 52.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.3 ft | Not graded |
| Phosphorus | 20 µg/L | Not graded |
| Chlorophyll-a (Algae) | 9.7 µg/L | Not graded |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 104 acres |
No bathymetric survey has been published for Shawnee Mission Lake, so its depth is not documented here.
Fishing Shawnee Mission Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.125 m/yr | 2 |
| Phosphorus | ↓ Declining | +1.35 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -1.05 µg/L/yr | 2 |
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)
Graded lakes near Shawnee Mission Lake
Shawnee Mission Lake has no grade, but these lakes within a short drive do.
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. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Shawnee Mission Lake?
- Shawnee Mission Lake in Johnson County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. 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?
- The letter is 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)
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.