Naches STP
9731 US-12, Naches, WA 98937 · Yakima County · Publicly Owned Treatment Works
- Average flow
- 0.54 MGD
- Design flow
- 0.54 MGD
- NPDES permit
- WA0022586
- Administratively continued
- Permit expires
- September 2019
- Population served
- 830
- CWNS 2022
Naches STP is a publicly owned wastewater treatment works in Naches, Yakima County, Washington treating an average of 0.54 million gallons per day against a permitted design capacity of 0.54 MGD, serving about 830 residents. It discharges under NPDES permit WA0022586 (administratively continued), which expires in September 2019, with 40 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Naches STP.
Available with a free Klarifi account
See the full treatment train at Naches STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 40
- Effluent violations
- 40
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Naches STP.
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Nearby wastewater treatment plants in Washington
Yakima · 15 mi away
8.67 MGD
Ellensburg · 18 mi away
3.59 MGD
Kittitas · 22 mi away
0.18 MGD
Harrah · 23 mi away
0.03 MGD
Zillah · 28 mi away
0.08 MGD
Toppenish · 30 mi away
0.09 MGD
Zillah · 31 mi away
0.2 MGD
Toppenish · 31 mi away
0.66 MGD
Naches 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 November 20, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Activated sludge · Oxidation ditch · all terms