Multnomah County stormwater is regulated under Oregon DEQ MS4 permits. Portland holds a Phase I NPDES permit and administers the Stormwater Management Manual (SWMM) under PCC 17.38. Post-construction runoff controls required for any development creating 500 sq ft or more of new impervious surface (stricter than the state 0.25-acre threshold). Clean River Rewards program incentivizes green infrastructure.
Portland's stormwater program is one of the most comprehensive in the US, built on a Phase I NPDES MS4 permit issued by Oregon DEQ. Portland City Code Chapter 17.38 (Drainage and Water Quality) and the Stormwater Management Manual (SWMM, last updated 2020 with 2023 amendments) require on-site stormwater management for any project creating or replacing 500 sq ft or more of impervious surface - stricter than the state minimum of 10,890 sq ft (0.25 acre) in OAR 340-041. Approved facilities include rain gardens, eco-roofs, pervious pavement, swales, drywells, and infiltration planters. The hierarchy prioritizes infiltration first, then filtration, then detention. Water quality facilities must treat the 90th percentile storm event. Clean Water Services for Washington County does not apply here, but Multnomah County unincorporated areas are served by Portland's Bureau of Environmental Services (BES) in sewer districts. Gresham holds its own Phase I MS4 permit with similar requirements under GRC 6.16. Columbia Slough watershed has additional TMDL requirements for bacteria and pollutants. Illicit discharge to storm drains (e.g., car wash water, paint, fluids) is prohibited under PCC 17.38.034. Portland's Clean River Rewards program (PCC 17.36) provides stormwater fee discounts up to 35% for residents who manage stormwater on-site.
Failure to implement stormwater plan: PCC 17.38.046 civil penalty $500 to $25,000 per violation plus stop-work. Illicit discharge: $500 to $10,000 per day under PCC 17.38.034. Post-construction facility neglect: $250 to $2,500 plus required retrofit. Federal NPDES violations: up to $56,460/day per 2024 EPA schedule.
Gresham, OR
Gresham addresses barking dogs through noise and animal control ordinances. Persistent barking that disturbs neighbors is a violation enforceable through Cod...
Gresham, OR
Gresham permits construction activities between 7 AM and 10 PM per GRC §7.20. Construction noise outside these hours is prohibited in residential areas.
Gresham, OR
Gresham Revised Code §7.20 regulates noise. Residential areas must not exceed 50 dBA between 10 PM and 7 AM, or 60 dBA between 7 AM and 10 PM at the property...
Gresham, OR
Gresham regulates on-street parking with time limits in certain areas. Vehicles must be currently registered and operable. Abandoned vehicles are subject to ...
Gresham, OR
Gresham requires driveways to meet development code standards. Vehicles must not block sidewalks or extend into the public right-of-way. Driveway modificatio...
Gresham, OR
Gresham restricts commercial vehicle parking in residential zones. Large commercial vehicles and heavy equipment may not be stored in residential areas.
Side-by-side rule comparisons with other cities in Multnomah County.
See how other cities in Multnomah County handle stormwater management.
See how Gresham's stormwater management rules stack up against other locations.
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