Is Big Creek Lake Polluted?
Yes — Big Creek Lake in Polk County, Iowa is on the EPA's Clean Water Act 303(d) impaired-waters list (2024 assessment cycle). It is cited for Algal growth, Pathogens (E. coli, fecal). A formal cleanup plan — a Total Maximum Daily Load (TMDL) — has been written. "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) | Completed |
| Assessment cycle | 2024 |
| EPA IR category | 5 |
| Location | Polk County, Iowa |
Pollutants Cited
- Algal growth — listed by EPA as exceeding water-quality standards for at least one designated use.
- Pathogens (E. coli, fecal) — listed by EPA as exceeding water-quality standards for at least one designated use.
Specific parameters in the EPA record: CHLOROPHYLL-A, ESCHERICHIA COLI (E. COLI).
What this means for using Big Creek Lake
Because Big Creek Lake is listed for Pathogens (E. coli, fecal), swimming can be affected — check for posted beach advisories, especially after heavy rain or during visible algae. 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. Big Creek Lake carries an overall water-quality grade of F, with algae (chlorophyll-a) at 35.7 µg/L and phosphorus at 80 µg/L — see the full breakdown on the lake report. The official EPA assessment is available in the ATTAINS waterbody report.
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