City Of Sioux City STP
3100 S Lewis Blvd, Sioux City, IA 51106 · Woodbury County · Publicly Owned Treatment Works
- Average flow
- 14.01 MGD
- Design flow
- 28.73 MGD
- NPDES permit
- IA0043095
- Effective
- Permit expires
- January 2031
- Population served
- 94,220
- CWNS 2022
City Of Sioux City STP is a publicly owned wastewater treatment works in Sioux City, Woodbury County, Iowa treating an average of 14.01 million gallons per day against a permitted design capacity of 28.73 MGD, serving about 94,220 residents. It discharges under NPDES permit IA0043095 (effective), which expires in January 2031, with 10 recorded violations in the last three years. EPA has recorded 1 formal enforcement action naming the plant, the latest in December 2013.
Treatment technology
2 treatment structures and unit processes identified at City Of Sioux City STP.
Available with a free Klarifi account
See the full treatment train at City Of Sioux City STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 10
- Effluent violations
- 10
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 City Of Sioux City STP in EPA's ICIS system.
- Formal actions
- 1
- 0 since FY2020
- Penalties assessed
- $17,500
- all cases
- EPA inspections
- 1
- latest Oct 2002
Latest case · Dec 2013
SIOUX CITY, IOWA (THE CITY OF)
Administrative order · CWA, Effluent Limitations - NPDES Toxic & Pretreatment Effluent Standards · Final Order With Penalty · Penalty $17,500
Source: EPA ECHO, civil enforcement case 07-2012-0222.
Full case history with a free Klarifi account
Every action against City Of Sioux City STP with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
Industrial users and pretreatment
Industries that discharge process wastewater to City Of Sioux City STP, from the plant's pretreatment programme records.
- Industrial users
- 8
- on record
Among them: Aramark Uniform Services- Sioux City (Sioux City); Darling International (Sioux City); Ipc Interstate Powder Coatings (Sioux City). Most users are in chemicals, plastics and petroleum and food and beverage.
Industrial users of City Of Sioux City STP →
Unlock all 8 industrial users of this plant
Discharge flow, federal category, source documents and contacts for every industrial user of City Of Sioux City STP. Free with a Klarifi account.
Capital improvement projects in Sioux City
Sioux City's capital improvement plan lists 28 water, sewer and wastewater line items worth $260M starting 2026–2028. The largest budgeted items are shown here.
All water and sewer capital projects in Sioux City →
| Project | Budget | Years |
|---|---|---|
| WWTP Facility Plan Improvements | $170,000,000 | 2027–2028 |
| Annual Water System Improvements | $12,051,000 | 2026–2030 |
| Outer Drive Pressure and Storage | $11,738,200 | 2028–2028 |
| Annual Sanitary Sewer Improvements | $11,460,000 | 2026–2030 |
| Annual Undersized Water Main Replacements | $9,390,000 | 2026–2030 |
Full project details — scope, funding source, engineering consultant and the decision-makers behind each project — are available in Klarifi, along with similar wastewater capital projects in other cities.
Key contacts
2 verified contacts for City Of Sioux City STP, with validated emails and direct phone numbers.
Unlock 2 verified contacts
Names, validated emails and direct phone numbers for decision-makers at City Of Sioux City STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Iowa
Lawton · 10 mi away
—
Salix · 11 mi away
—
Hinton · 12 mi away
0.04 MGD
Moville · 15 mi away
0.1 MGD
Sloan · 16 mi away
0.08 MGD
Merrill · 20 mi away
0.04 MGD
Hornick · 21 mi away
—
Kingsley · 22 mi away
0.18 MGD
City Of Sioux City 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 May 17, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Ozonation · Activated sludge · all terms