Granite Falls STP
500 W Wallace St, Granite Falls, WA 98252 · Snohomish County · Publicly Owned Treatment Works
- Average flow
- 0.41 MGD
- Design flow
- 1.67 MGD
- NPDES permit
- WA0021130
- Administratively continued
- Permit expires
- July 2025
- Population served
- 3,858
- CWNS 2022
Granite Falls STP is a publicly owned wastewater treatment works in Granite Falls, Snohomish County, Washington treating an average of 0.41 million gallons per day against a permitted design capacity of 1.67 MGD, serving about 3,858 residents. It discharges under NPDES permit WA0021130 (administratively continued), which expires in July 2025, with 6 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Granite Falls STP.
Available with a free Klarifi account
See the full treatment train at Granite Falls STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 6
- Effluent violations
- 6
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Granite Falls STP.
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Nearby wastewater treatment plants in Washington
Marysville · 14 mi away
0.2 MGD
Monroe · 16 mi away
1.79 MGD
Sultan · 17 mi away
0.59 MGD
Stanwood · 21 mi away
0.67 MGD
Edmonds · 21 mi away
2.45 MGD
Edmonds · 23 mi away
3.96 MGD
Mount Vernon · 25 mi away
0.19 MGD
Burlington · 31 mi away
1.56 MGD
Granite Falls 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 29, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Activated sludge · Oxidation ditch · all terms