Is Crystal Lake Max Depth Polluted?
Yes — Crystal Lake Max Depth in Hancock County, Iowa is on the EPA's Clean Water Act 303(d) impaired-waters list (2024 assessment cycle). It is cited for Algal growth, Turbidity. 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 | Listed impaired |
| Cleanup plan (TMDL) | Completed |
| Assessment cycle | 2024 |
| EPA IR category | 4A |
| Location | Hancock County, Iowa |
Pollutants Cited
- Algal growth — listed by EPA as exceeding water-quality standards for at least one designated use.
- Turbidity — listed by EPA as exceeding water-quality standards for at least one designated use.
Specific parameters in the EPA record: CHLOROPHYLL-A, TURBIDITY.
What this means for using Crystal Lake Max Depth
Review the EPA assessment and any state advisories before relying on Crystal Lake Max Depth 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. Crystal Lake Max Depth carries an overall water-quality grade of F, with algae (chlorophyll-a) at 50.3 µg/L — see the full breakdown on the lake report. The official EPA assessment is available in the ATTAINS waterbody report.