Toppenish Wastewater Treatment Plant
501 Annahat Rd, Toppenish, WA 98948 · Yakima County · Publicly Owned Treatment Works
- Average flow
- 0.66 MGD
- Design flow
- 1.67 MGD
- NPDES permit
- WA0026123
- Effective
- Permit expires
- December 2030
- Population served
- 7,885
- CWNS 2022
Toppenish Wastewater Treatment Plant is a publicly owned wastewater treatment works in Toppenish, Yakima County, Washington treating an average of 0.66 million gallons per day against a permitted design capacity of 1.67 MGD, serving about 7,885 residents. It discharges under NPDES permit WA0026123 (effective), which expires in December 2030, with 29 recorded violations in the last three years. EPA has recorded 2 formal enforcement actions naming the plant, the latest in September 2025.
Treatment technology
2 treatment structures and unit processes identified at Toppenish Wastewater Treatment Plant.
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See the full treatment train at Toppenish Wastewater Treatment Plant: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 29
- Effluent violations
- 29
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 Toppenish Wastewater Treatment Plant in EPA's ICIS system.
- Formal actions
- 2
- 1 since FY2020
- Penalties assessed
- $134,500
- all cases
- Compliance actions
- $19M
- required by EPA orders
- EPA inspections
- 1
- latest Mar 2026
Latest case · Sep 2025
CITY OF TOPPENISH WWTP (ACO) (CWA NPDES)
Administrative order · CWA, NPDES Permit Violations · Final Order No Penalty · Compliance actions $8.2M
EPA's description of the case:
“On September 25, 2025, Region 10 issued an Administrative Order on Consent to the City of Toppenish to resolve CWA violations at its wastewater treatment facility in Toppenish, Washington. The order…”
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Source: EPA ECHO, civil enforcement case 10-2025-0157.
Full case history with a free Klarifi account
Every action against Toppenish Wastewater Treatment Plant with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
Key contacts
15 verified contacts for Toppenish Wastewater Treatment Plant, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at Toppenish Wastewater Treatment Plant, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Washington
Zillah · 2 mi away
0.2 MGD
Toppenish · 3 mi away
0.09 MGD
Zillah · 4 mi away
0.08 MGD
Granger · 5 mi away
0.17 MGD
Sunnyside · 13 mi away
1.34 MGD
Harrah · 13 mi away
0.03 MGD
Sunnyside · 14 mi away
1.64 MGD
Yakima · 17 mi away
8.67 MGD
Toppenish 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 July 25, 2026.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Equalization tank · Centrate · all terms