Pony Express Lake is a 164-acre productive, nutrient-rich eutrophic lake in DeKalb County, Missouri. Water quality is graded D based on 3 sampling years through 2024. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 5 other monitored lakes in DeKalb County, Pony Express Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-07. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 1.3 ft of visibility. Phosphorus level: 53.2 µg/L. Chlorophyll-a: 26.3 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | 53.2 µg/L | C |
| Chlorophyll-a (Algae) | 26.3 µg/L | D |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 164 acres |
| Public Access | Yes |
Where to stay near Pony Express Lake
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Fishing Pony Express Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.145 m/yr | 2 |
| Phosphorus | ↓ Declining | +3.54 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -5.41 µg/L/yr | 3 |
Recreation & Access
Water Temperature
Pony Express Lake averages about 80°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in May (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2016–2024) via the EPA Water Quality Portal. See the full Pony Express Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 6 lakes in DeKalb County
Nearby Lakes in DeKalb County
Explore Pony Express 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)
Pony Express Lake is a man-made reservoir impounded by the Pony Express Lake Dam (completed 1963), built primarily for recreation on the TR-WEST FORK LOST CREEK; earth-type dam, 40 ft tall and 1,600 ft long.
- Surface area
- 164 ac
- Normal storage
- 2,400 ac-ft
- Max storage
- 3,560 ac-ft
- Drainage area
- 4.14 sq mi
- Hazard class
- High
- Owner
- MO DEPT OF CONSERVATION
Source: USACE National Inventory of Dams, NID ID MO10171 · Operator website
EPA Impairment Status
Pony Express 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_7118.00 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-08-07
Monitoring stations: 2