Cottontail Lake
Jackson County, Missouri21 acresView mapDirections
Missouri DNR publishes the water-quality measurements for Cottontail Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Mercury
- Limited data
Cottontail Lake in Jackson County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 86.5 µg/L. Chlorophyll-a (algae): 39.4 µg/L. Surface area: 21 acres.
Cottontail Lake is a 21-acre highly nutrient-loaded hypereutrophic lake in Jackson County, Missouri. Overall water quality is declining over recent sampling years. Compared to the 22 other monitored lakes in Jackson County, Cottontail Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2023-10-03. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Cottontail Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Cottontail Lake is safe to swim in today is a call for the Missouri Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cottontail Lake
These are the measurements Missouri DNR publishes for Cottontail Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.6 ft of visibility. Phosphorus 86.5 µg/L. Chlorophyll-a 39.4 µg/L. TSI 68.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 86.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 39.4µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 68 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Cottontail Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
21 acres
No bathymetric survey has been published for Cottontail Lake, so its depth is not documented here.
Stays via Stay22
Stays near Cottontail Lake
Compare lakeside cabins, hotels, and vacation rentals near Cottontail Lake in Jackson County, Missouri — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Cottontail Lake are listed below.
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Fishing Cottontail Lake
Water Quality Trend: Worsening
Based on 5 years of monitoring (2020–2024).
Water clarity
Worsening4 years
Phosphorus
Worsening+12.62 µg/L/yr5 years
Chlorophyll-a
Worsening+5.57 µg/L/yr5 years
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
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MO_7379.00 · Official waterbody report
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.
Nearby Lakes in Jackson County
Frequently asked questions about Cottontail Lake
Where is Cottontail Lake?
- Cottontail Lake is a lake in Jackson County, Missouri. Its water-quality measurements are published by Missouri DNR and shown on this page as reported.
What is the water quality of Cottontail Lake?
- Cottontail Lake in Jackson County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 86.5 µg/L. Chlorophyll-a (algae): 39.4 µg/L. Surface area: 21 acres.
Is Cottontail Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Cottontail Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Explore Cottontail Lake across LakeQuality
More lakes in Missouri
Other Lakes in Missouri
Hypereutrophic Lakes in Missouri
Where this data comes from
23 measurements from 2 monitoring stations, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC20 samples · 2020 - Missouri Dept. of Natural Resources
MDNR3 samples · 2023
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Nitrogen and Phosphorus, Total, Whole-water, Alkaline Persulfate Digest
Monitoring station identifiers (2)
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)