Zillah Wastewater Treatment Plant
740 Railroad Ave, Zillah, WA 98953 · Yakima County · Publicly Owned Treatment Works
- Average flow
- 0.2 MGD
- Design flow
- 1.47 MGD
- NPDES permit
- WA0020168
- Effective
- Permit expires
- October 2030
- Population served
- 3,434
- CWNS 2022
Zillah Wastewater Treatment Plant is a publicly owned wastewater treatment works in Zillah, Yakima County, Washington treating an average of 0.2 million gallons per day against a permitted design capacity of 1.47 MGD, serving about 3,434 residents. It discharges under NPDES permit WA0020168 (effective), which expires in October 2030, with 0 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Zillah Wastewater Treatment Plant.
Available with a free Klarifi account
See the full treatment train at Zillah Wastewater Treatment Plant: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Zillah Wastewater Treatment Plant.
No verified contacts on file yet
Klarifi verifies plant and municipal decision-makers continuously. Start a free trial to browse contacts at nearby plants and flag this one for verification.
Nearby wastewater treatment plants in Washington
Toppenish · 2 mi away
0.66 MGD
Zillah · 3 mi away
0.08 MGD
Toppenish · 4 mi away
0.09 MGD
Granger · 5 mi away
0.17 MGD
Sunnyside · 13 mi away
1.34 MGD
Sunnyside · 14 mi away
1.64 MGD
Harrah · 14 mi away
0.03 MGD
Yakima · 16 mi away
8.67 MGD
Zillah Wastewater Treatment Plant: 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 29, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · FOG · Equalization tank · all terms