Remeandering: A Chance to Revisit Choices Made Decades Before

Fanno Creek originates in Portland’s West Hills and runs through the city of Tigard from its northern border with Beaverton to its southern edge at the confluence with the Tualatin River. In the 1970s, while installing a sewer pipe in preparation for the coming population boom, the Unified Sewerage Agency (now Clean Water Services) straightened a short reach of Fanno Creek just south of Main Street. For decades after this intervention, the once-meandering, now ditch-like creek was not only unnatural looking but also ecologically unstable.

By the early 2000s, Clean Water Services and the City of Tigard had identified creek remeandering as a priority. Yet it took more than a decade to align the resources to make the project happen. Today, thanks to the actions of Tree for All partners, a healthier and more naturally flowing stream runs through Fanno Creek Park, making positive contributions to the economic, ecological and community health of downtown Tigard.

Fanno Creek: Ash-to-Main

Revegetation began in 2019. Bareroot trees and shrubs, as well as a diverse array of native herbaceous species will help stabilize the creek banks and create wildlife habitat.

A new pedestrian bridge connects upgraded trails in Fanno Creek Park. The new bridge is higher than the old one, which constrained the creek and sometimes flooded the trail.

In the heart of Tigard, the remeandered creek and floodplain are easily accessible to park-goers.

Ash-to-Main is the latest of many ecologically enhanced segments of Fanno Creek, one of Washington County’s most urban waterways.

The Ash-to-Main project uses highly effective revegetation tactics, including soil lifts, custom native seed blends, and bareroot trees and shrubs.

Fanno Creek, once a symbol of urban pollution, has become a popular walking, running and biking destination.

download the case study

The Site

First planting: 2019
Size: 6.5 acres
Stream length: .25 miles
Plant communities: Riparian Forest, Scrub Shrub Wetland

Featured

Habitat Connectivity

Keystone Species

Recreation and Human Health

Community Involvement

Urban Partnership

Protects Water Quality

Floodplain Access

The Challenge

Without natural curves to help dissipate the energy of the flowing water, this portion of Fanno Creek became prone to erosion. Invasive plants and poor water quality followed, as did trails prone to flooding and at risk of crumbling into the creek. During high flows, a pedestrian bridge that obstructed creek flow contributed to the flooding. While the creek itself was straight, considerable twists and turns stood in the path between identifying it as an ecological enhancement priority and actually breaking ground on a project.

The Transformation

In 2007, the City of Tigard and Clean Water Services began to lay the groundwork for what would become known as the Fanno Creek Remeander Project. The goal was to reduce erosion, thereby improving water quality, wildlife habitat and the pedestrian experience in Fanno Creek Park between SW Ash and SW Main Streets. Almost a decade later, the timing was right and the resources were aligned to embark upon a project that would:

Create a better-functioning channel for Fanno Creek, closer to what it would have been before the creek was straightened.
Improve floodplain wetlands and streambanks through revegetation of native riparian and wetland plants.
Replace the Ash Street pedestrian bridge with a new one that gives both people and water more room to move.
Add an overlook and pedestrian/bike trails that follow Fanno Creek.

As is true with most Tree for All projects that involve construction in streams and rivers, much of the on-the-ground activity needed to take place during the “in-water work window” that, in our area, begins in mid-July and runs through September.

Construction took place in the summer of 2018. A new channel was excavated; the old one was filled. The pedestrian bridge was replaced. Streambanks were stabilized for winter. (For example, some were constructed of soil lifts, layers of soil wrapped in coconut fiber blankets, with dogwood branches placed horizontally between them.)

In the spring of 2019, revegetation began. Professional forestry crews installed bareroot trees and shrubs, as well as a diverse array of native herbaceous species—all carefully chosen to stabilize the creek banks and create important wildlife habitat. In time, they will mature into a plant community that prevents erosion, shades the creek, and adds to the aesthetic appeal of the area.