Is Pony Express Lake Polluted?
Yes — Pony Express Lake in DeKalb County, Missouri is on the EPA's Clean Water Act 303(d) impaired-waters list (2022 assessment cycle). It is cited for Algal growth. No cleanup plan (TMDL) has been completed yet. "Impaired" is a legal designation, separate from the lake's A–F water-quality grade: it means at least one designated use (such as swimming, aquatic life, or fish consumption) does not meet state standards for the listed pollutant.
EPA 303(d) Listing
| On 303(d) impaired list | Yes |
| Cleanup plan (TMDL) | Not yet written |
| Assessment cycle | 2022 |
| EPA IR category | 5 |
| Location | DeKalb County, Missouri |
Pollutants Cited
- Algal growth — listed by EPA as exceeding water-quality standards for at least one designated use.
Specific parameters in the EPA record: CHLOROPHYLL-A.
What this means for using Pony Express Lake
Review the EPA assessment and any state advisories before relying on Pony Express Lake for swimming, fishing, or other uses. An impairment listing does not mean the lake is closed — most impaired lakes remain open for boating and swimming. It means a specific pollutant exceeds a standard for a specific use. Pony Express Lake carries an overall water-quality grade of D, with algae (chlorophyll-a) at 26.3 µg/L and phosphorus at 53.2 µg/L — see the full breakdown on the lake report. The official EPA assessment is available in the ATTAINS waterbody report.