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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

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I-5 and SW 26th Avenue Terraced Rain Gardens Project

Environmental Services and the Oregon Department of Transportation (ODOT) completed a series of terraced rain gardens in summer 2015 at the intersection of Interstate 5, SW Barbur Boulevard and SW 26th Avenue. The project collects and treats stormwater runoff from 24 acres of roads to protect water quality in Tryon Creek.

completed terraced rain garden construction
terraced rain gardens soon after completing construction

terraced rain gardens managing stormwater
terraced rain gardens managing stormwater during a rainstorm

This is the largest rain garden project to date in Portland, and is part of efforts to improve stormwater management in the Tryon Creek Watershed and other parts of southwest Portland.

Before the project, stormwater runoff from these roads drained directly into Tryon Creek, carrying pollutants and causing high flows and erosion. Now, the water flows into a forebay that captures sediment and pollutants. The water then flows through a series of rain gardens that slow the velocity and allow more pollutants to settle before reaching the creek.

rain garden site before construction
rain garden site before construction

Over 11,000 native trees and shrubs planted on the site help reduce stormwater volume and pollution and provide other benefits, like filtering air pollutants, providing habitat, and absorbing carbon to reduce greenhouse gases.

planting trees and shrubs in the rain garden
planting native trees and shrubs in the rain garden

Watershed Health Index
This project improves water quality by treating 24 million gallons of stormwater each year before it flows to Tryon Creek. This helps the creek’s salmon and other fish and wildlife.

Learn more in the Tryon Creek Watershed Report Card.