Stormwater Management: Gresham vs Troutdale
How do stormwater management rules compare between Gresham, OR and Troutdale, OR?
Gresham and Troutdale have similar restriction levels.
Gresham, OR
Multnomah County
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.
View full Gresham rules →Troutdale, OR
Multnomah County
Troutdale operates a municipal stormwater system under an NPDES Phase II MS4 General Permit issued by Oregon DEQ. Storm sewer rules are codified in Troutdale Municipal Code (TMC) Chapter 12.06 (Storm Sewer System) and erosion and sediment control in TMC Chapter 12.09. The Public Works Department's Stormwater Services Division responds to spills and illicit discharges; report a spill via 503-674-3300 (business hours) or 503-251-4163 (after-hours emergency).
View full Troutdale rules →Key Facts Comparison
| Fact | Gresham | Troutdale |
|---|---|---|
| Portland Code | PCC 17.38; SWMM | - |
| Impervious Trigger | 500 sq ft (PDX) | - |
| State Trigger | 10,890 sq ft | - |
| Regulator | DEQ + Portland BES | - |
| Program | Clean River Rewards | - |
| City Code | - | TMC Ch. 12.06 (Storm Sewer) + Ch. 12.09 (Erosion) |
| Permit | - | Oregon DEQ NPDES Phase II MS4 General Permit |
| Receiving Waters | - | Sandy River and Columbia River |
| Construction Permit | - | DEQ 1200-C (1+ acre disturbance) |
| Report Spill (business hr) | - | Public Works 503-674-3300 |
| Report Spill (after hours) | - | 503-251-4163 |
Highlighted rows indicate differences between cities.
Gresham FAQ
Do I need stormwater controls for a new driveway?
In Portland, yes if the new/replaced impervious surface totals 500 sq ft or more. Small residential patches below that may be exempt but check with BDS during permitting.
Can I wash my car in the driveway?
It is discouraged. Soapy water flowing to storm drains violates PCC 17.38.034. Use a commercial car wash or wash on gravel/grass where water infiltrates.
Troutdale FAQ
What is illegal to put in a Troutdale storm drain?
Anything other than uncontaminated rainwater. TMC Chapter 12.06 prohibits illicit discharges including motor oil, antifreeze, paint, soaps, vehicle wash water, sediment from construction, pet waste, yard waste, fertilizers, and chemicals. Storm drains in Troutdale discharge to the Sandy and Columbia Rivers, which support threatened salmon.
How do I report a spill or illicit discharge in Troutdale?
Call Troutdale Public Works at 503-674-3300 during business hours or 503-251-4163 for after-hours emergencies. The city also accepts online spill reports through a survey form linked from the Stormwater Services page. For active threats to life or property, call 911.
Does Troutdale require erosion control on construction sites?
Yes. TMC Chapter 12.09 governs construction-site erosion and sediment control. Projects disturbing 1 acre or more also need Oregon DEQ's NPDES 1200-C Construction General Permit. Plans typically must include perimeter sediment controls, inlet protection, stabilized construction entrances, and stockpile protection.
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