Iowa City, City Of (south) STP
4366 Napoleon St. SE, Iowa City, IA 52240 · Johnson County · Publicly Owned Treatment Works
- Average flow
- 8.98 MGD
- Design flow
- 43.3 MGD
- NPDES permit
- IA0070866
- Effective
- Permit expires
- July 2030
- Population served
- 22,457
- CWNS 2022
Iowa City, City Of (south) STP is a publicly owned wastewater treatment works in Iowa City, Johnson County, Iowa treating an average of 8.98 million gallons per day against a permitted design capacity of 43.3 MGD, serving about 22,457 residents. It discharges under NPDES permit IA0070866 (effective), which expires in July 2030, with 11 recorded violations in the last three years. EPA has recorded 1 formal enforcement action naming the plant, the latest in December 2022.
Treatment technology
4 treatment structures and unit processes identified at Iowa City, City Of (south) STP.
Available with a free Klarifi account
See the full treatment train at Iowa City, City Of (south) STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 11
- Effluent violations
- 11
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
EPA enforcement history
Federal civil enforcement cases, compliance inspections and informal actions recorded for Iowa City, City Of (south) STP in EPA's ICIS system.
- Formal actions
- 1
- 1 since FY2020
- Compliance actions
- $125,467
- required by EPA orders
- EPA inspections
- 0
- none on record
Latest case · Dec 2022
IOWA CITY, IOWA
Administrative order · CWA, NPDES Permit Violations · Final Order No Penalty · Compliance actions $125,467
EPA's description of the case:
“Respondent failed to comply with effluent limitations and permit conditions required by Respondent?s NPDES Permit pursuant to Section 402 of the Clean Water Act.”
Source: EPA ECHO, civil enforcement case 07-2020-0103.
Full case history with a free Klarifi account
Every action against Iowa City, City Of (south) STP with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
Key contacts
26 verified contacts for Iowa City, City Of (south) STP, with validated emails and direct phone numbers.
Unlock 26 verified contacts (23 more than shown)
Names, validated emails and direct phone numbers for decision-makers at Iowa City, City Of (south) STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Iowa
Hills · 5 mi away
0.16 MGD
Coralville · 7 mi away
2.98 MGD
North Liberty · 9 mi away
2.03 MGD
West Branch · 9 mi away
0.49 MGD
Lone Tree · 10 mi away
0.3 MGD
Riverside · 10 mi away
0.17 MGD
Tiffin · 10 mi away
0.52 MGD
West Liberty · 13 mi away
2.41 MGD
Iowa City, City Of (south) STP: frequently asked 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 October 26, 2026; facility record last updated March 28, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Biological nutrient removal · Tertiary treatment · all terms