Portland, OR Environmental Rules: Stormwater Management (2026)

Stormwater must be managed in as close proximity to the development or redevelopment site as is practicable. This section is intended to prevent a net negative impact on nearby streams, wetlands, groundwater, and other water bodies. All local, state, and federal permit requirements related to implementation of stormwater management facilities must be met by the owner/operator prior to facility use.

1. The City may enter into agreements with property owners to manage stormwater flows through methods other than onsite controls:

a. In facilities where public and private property flows co-mingle.

b. In offsite managed areas that are “traded” for required onsite management areas related to new development and redevelopment. The City may require more than a 1:1 exchange on the amount of required management area.

2. All discharges from a site must be routed through a discharge point to a receiving system as approved by the City Administrator. Approval of discharge points is subject to the following:

a. The discharge must be conveyed along a route of service approved by the City Administrator.

b. The discharge point must comply with the following:

(1) The Sewer and Drainage Facilities Design Manual and the Source Control Manual, for sanitary, wastewater, or other discharges to the sanitary or combined system.