Activated sludge and clarifiers: wastewater treatment plants in Iowa
83 plants · 12% of the state · no reported flow
Klarifi identifies 83 publicly owned wastewater treatment plants with activated sludge and clarifiers in Iowa, 12% of the 678 plants in the state (no reported flow). The largest is Shellsburg WWTP in Shellsburg at 0.13 MGD.
Activated sludge is the standard mechanical process for cities: aeration basins where bacteria consume organic matter, followed by clarifiers that settle the biomass out. These plants are identified by their circular or rectangular clarifiers and by the suspended-growth process code, and they are the main market for blowers, diffusers, clarifier mechanisms and instrumentation.
The largest activated sludge plants in Iowa
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Shellsburg WWTP | Shellsburg | 0.13 | IA0033332 | May 2006 | 0 |
| 2 | Adair WWTP | Adair | — | IA0035416 | Jul 2029 | 4 |
| 3 | Algona City Of STP | Algona | — | IA0022055 | Feb 2028 | 13 |
| 4 | Anamosa WWTP | Anamosa | — | IA0025895 | Mar 2031 | 12 |
| 5 | Asbury City Of STP | Asbury | — | IA0069922 | Oct 2029 | 1 |
| 6 | Belmond City Of STP | Belmond | — | IA0041777 | Sep 2026 | 43 |
| 7 | Burlington, City Of (wwtp) | Burlington | — | IA0043079 | Jan 2027 | 4 |
| 8 | Carroll WWTP | Carroll | — | IA0021377 | Aug 2027 | 1 |
| 9 | Carson City Of STP | Carson | — | IA0042901 | Dec 2026 | 13 |
| 10 | Cedar Falls City Of STP | Cedar Falls | — | IA0036633 | Dec 2029 | 0 |
| 11 | Centerville City Of STP (east) | Centerville | — | IA0027472 | May 2029 | 23 |
| 12 | Centerville City Of STP (west) | Centerville | — | IA0027464 | May 2029 | 33 |
| 13 | Chariton City Of STP | Chariton | — | IA0028924 | Jul 2029 | 15 |
| 14 | Cherokee WWTP | Cherokee | — | IA0059005 | Jan 2026 | 81 |
| 15 | City Of Boone Water Pollution Control | Boone | — | IA0058076 | Nov 2029 | 3 |
| 16 | City Of Emmetsburg Treatment Plant | Emmetsburg | — | IA0021580 | Apr 2031 | 77 |
| 17 | City Of Muscatine Water & Resource Recovery Facility | Muscatine | — | IA0023434 | Mar 2030 | 20 |
| 18 | City Of Pella | Pella | — | IA0043869 | Mar 2027 | 0 |
| 19 | City Of Shenandoah STP | Shenandoah | — | IA0032328 | Jan 2027 | 75 |
| 20 | City Of Sioux City STP | Sioux City | — | IA0043095 | Jan 2031 | 10 |
| 21 | Clinton WWTP | Clinton | — | IA0035947 | Jun 2031 | 12 |
| 22 | Coralville WWTP | Coralville | — | IA0020788 | Mar 2026 | 1 |
| 23 | Council Bluffs City Of STP | Council Bluffs | — | IA0036641 | Aug 2031 | 0 |
| 24 | Cresco WWTP | Cresco | — | IA0021334 | Jun 2026 | 12 |
| 25 | Creston City Of STP | Creston | — | IA0035238 | Dec 2025 | 3 |
Plants planning activated sludge and clarifiers upgrades
These plants report activated sludge and clarifiers as a planned process in the EPA Clean Watersheds Needs Survey: the earliest public signal of a project.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires |
|---|---|---|---|---|
| Park View Water Co | Eldridge | — | IA0062561 | Jun 2028 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in Iowa
Activated sludge and clarifiers in other states
Activated sludge and clarifiers in Iowa: questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026.