Pony Express Lake
DeKalb County, Missouri164 acresView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- Impaired · Algal growth
- #1 of 5 in the county
- 31 ft max depth
- Public access
- Limited data
Pony Express Lake in DeKalb County, Missouri has a water quality grade of D (Nutrient-rich). Water clarity: 1.3 ft visibility. Phosphorus: 53.2 µg/L. Chlorophyll-a (algae): 26.3 µg/L. Surface area: 164 acres.
- Clarity
- 1.3 ft
- Typical in August
- 80°F
- Max depth
- ~31 ft est.
- Area
- 164 acres
- Type
- Eutrophic
- Phosphorus
- 53.2 µg/L
- Chlorophyll-a
- 26.3 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Pony Express Lake
Compare lakeside cabins, hotels, and vacation rentals near Pony Express Lake in DeKalb 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 grade measures nutrients and algae, not lodging — cabins and rentals around Pony Express Lake are listed below.
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Pony Express Lake is a 164-acre productive, nutrient-rich eutrophic lake in DeKalb County, Missouri with an estimated average depth of about 31 feet. Water quality is graded D based on 2 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 4 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: LakeQuality methodology.
What Pony Express Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch3 documented ramps
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The D is nutrients and algae, not a swimming clearance. Pony Express Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 1.3 ft of visibility. Phosphorus 53.2 µg/L. Chlorophyll-a 26.3 µg/L. TSI 66. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | Not graded |
| Phosphorus | 53.2 µg/L | Fair |
| Chlorophyll-a (Algae) | 26.3 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Pony Express Lake typically sits around 80°F at the surface in August. Summer average is about 80°F. 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 →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~31 ft est. |
| Average Depth | ~13 ft est. |
| Surface Area | 164 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Missouri has not published bathymetry for Pony Express Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Pony Express Lake Conservation AreaPublic
- Pony Express Lake Conservation AreaPublic
- Pony Express Lake Conservation AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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 |
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
County Ranking
Ranked #1 of 5 lakes in DeKalb County
Nearby Lakes in DeKalb County
Frequently asked questions about Pony Express Lake
Where is Pony Express Lake?
- Pony Express Lake is a lake in DeKalb County, Missouri. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Pony Express Lake?
- Pony Express Lake in DeKalb County, Missouri has a water quality grade of D (Nutrient-rich). Water clarity: 1.3 ft visibility. Phosphorus: 53.2 µg/L. Chlorophyll-a (algae): 26.3 µg/L. Surface area: 164 acres.
Is Pony Express Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Pony Express Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
What is the water temperature of Pony Express Lake?
- Pony Express Lake typically sits around 80°F at the surface in August, from 10 EPA Water Quality Portal field readings (2016–2024). That is a typical value for the month, not a live reading.
How deep is Pony Express Lake?
- No published bathymetric survey covers Pony Express Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 31 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 164 acres.
Are there boat ramps on Pony Express Lake?
- Pony Express Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Pony Express Lake Conservation Area, Pony Express Lake Conservation Area, Pony Express Lake Conservation Area. Public access is listed as yes.
Explore Pony Express Lake across LakeQuality
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Where this data comes from
11 measurements from 2 monitoring stations, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC8 samples · 2024 - Missouri Dept. of Natural Resources
MDNR3 samples · 2023
Analytical methods
- Depth, Secchi disk in meters
- Nitrogen and Phosphorus, Total, Whole-water, Alkaline Persulfate Digest
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
Monitoring station identifiers (2)
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory