Cottontail Lake is a 21-acre productive, nutrient-rich eutrophic lake in Jackson County, Missouri. Water quality is graded F based on 3 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 26 other monitored lakes in Jackson County, Cottontail Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2023-10-03. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.6 ft of visibility. Phosphorus level: 86.5 µg/L. Chlorophyll-a: 39.4 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | F |
| Phosphorus | 86.5 µg/L | D |
| Chlorophyll-a (Algae) | 39.4 µg/L | F |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 21 acres |
Where to stay near Cottontail Lake
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Fishing Cottontail Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.039 m/yr | 4 |
| Phosphorus | ↓ Declining | +12.62 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +5.57 µg/L/yr | 5 |
Location
County Ranking
Ranked #11 of 27 lakes in Jackson County
Cleaner Lakes Within 30 Miles
Cottontail Lake holds Grade F. 2 nearby lakes hold higher grades.
- CLotawana Lk. LakeJackson County · 5.1 mi · Two grade letters higher (F → C)
- DPrairie Lee Lake Nr. DamJackson County · 4.2 mi · Higher grade (F → D)
Nearby Lakes in Jackson County
Explore Cottontail Lake across LakeGrade
More Missouri Lake Rankings
Other Grade F Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
Reservoir Info (USACE NID)
Cottontail Lake is a man-made reservoir impounded by the Cottontail Lake Dam (completed 1966), built primarily for recreation on the TR-EAST BR-BIG CREEK; earth-type dam, 25 ft tall.
- Surface area
- 21 ac
- Normal storage
- 154 ac-ft
- Max storage
- 281 ac-ft
- Drainage area
- 1,200 sq mi
- Hazard class
- Low
- Owner
- MO DEPT OF CONSERVATION
Source: USACE National Inventory of Dams, NID ID MO20025 · Operator website
EPA Impairment Status
Cottontail Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MO_7379.00 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Cottontail Lake under Clean Water Act (NPDES) discharge permits.
- Woodland Elementary School WwtpLee'S Summit · 0.8 mi away · NPDES MO0125351
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-10-03
Monitoring stations: 2