Watkins Mill Lake is a 100-acre productive, nutrient-rich eutrophic lake in Clay County, Missouri. Water quality is graded D based on 3 sampling years through 2024. Water clarity is declining over recent sampling years. Compared to the 8 other monitored lakes in Clay County, Watkins Mill Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-07. Grade methodology: LakeGrade methodology.
Watch Watkins Mill Lake water quality
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Swimming Safety
Based on E. coli testing, Watkins Mill Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 11.7% of 264 samples across 8 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Missouri’s current beach and health-department advisories before swimming.
Water Quality Grade: D, Poor
Very murky, less than 3.2 ft of visibility. Phosphorus level: 41 µg/L. Chlorophyll-a: 18.2 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.2 ft | F |
| Phosphorus | 41 µg/L | C |
| Chlorophyll-a (Algae) | 18.2 µg/L | C |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 100 acres |
Where to stay near Watkins Mill Lake
Compare lakeside cabins, hotels, and vacation rentals near Watkins Mill Lake in Clay 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.
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Fishing Watkins Mill Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.08 m/yr | 4 |
| Phosphorus | → Stable | -0.1 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -2.29 µg/L/yr | 5 |
Water Temperature
Watkins Mill Lake averages about 82°F at the surface in summer, usually warmest in Jul (about 84°F) and coldest in May (about 74°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 63 field readings (2010–2024) via the EPA Water Quality Portal. See the full Watkins Mill Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 9 lakes in Clay County
Nearby Lakes in Clay County
Explore Watkins Mill Lake across LakeGrade
More Missouri Lake Rankings
Other Grade D Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
Reservoir Info (USACE NID)
Watkins Mill Lake is a man-made reservoir impounded by the Watkins Mill State Park Dam (completed 1971), built primarily for recreation on the TR-WILLIAMS CREEK; earth-type dam, 55 ft tall and 1,600 ft long.
- Surface area
- 100 ac
- Normal storage
- 2,600 ac-ft
- Max storage
- 2,600 ac-ft
- Drainage area
- 2.95 sq mi
- Hazard class
- High
- Owner
- MO. DNR PARKS
All listed purposes: Recreation;Flood Risk Reduction.
Source: USACE National Inventory of Dams, NID ID MO10011 · Operator website · Matched by proximity (0.11 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
9 EPA-permitted facilities operate within about 5 miles of Watkins Mill Lake under Clean Water Act (NPDES) discharge permits. 5 facilities have a reported Clean Water Act violation in the past three years.
- Shelton Estates WwtfExcelsior Springs · 2.2 mi away · NPDES MO0103276Recent violation
- Excelsior Estates WwtpLawson · 3.3 mi away · NPDES MO0108511Recent violation
- Indian Ridge Mobile Home Court WwtfExcelsior Springs · 3.9 mi away · NPDES MO0107492Recent violation
- Homestead Village WwtpExcelsior Springs · 4 mi away · NPDES MO0056545Recent violation
- Mawc, Lawson LagoonLawson · 4.5 mi away · NPDES MO0091031Recent violation
- Watkins Woolen Mill State Park & StateLawson · 0.2 mi away · NPDES MO0034959
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-08-07
Monitoring stations: 2