The Ribbon of Healthy Creek Grows Longer

Fanno Creek originates in the Tualatin Mountains (Portland’s West Hills) and travels almost 17 urban miles on its way to the Tualatin River. Just after crossing under Highway 217, it enters the Fanno Creek Greenway, a Tualatin Hills Park & Recreation District property with trails that draw more than 100,000 visitors a year. Years ago, a portion of the creek between Denney Road and Hall Boulevard was straightened, leading to eroding stream beds and banks. Wildlife habitat and water quality suffered. In addition, a pair of undersized culverts has impaired fish passage and contributed to frequent trail flooding.

The Denney-to-Hall project, slated for construction in the summer of 2019 and revegetation in 2020, will replace the culverts with a pedestrian bridge, restore curves to the creek’s path and improve plant and animal habitat. Like earlier Tree for All projects on other portions of Fanno Creek, Denney-to-Hall is an exciting opportunity to support a healthy floodplain in an intensely urban environment.


The Site

First planting: 2020
Size: 21 acres
Stream length: 3,021 feet
Plant communities: Forested Wetland, Riparian Forest, Scrub Shrub

 

The Challenge

Like the Ash-to-Main project a few miles downstream, the Denney-to-Hall project will take on the challenge of erosion by “remeandering” the creek so that it follows a more natural path. The project design is shaped by the heavy presence of important water infrastructure, including sanitary sewer lines and a stormwater outfall—as well as a pond and other remnants of a decommissioned sewage treatment facility. Another challenge—and opportunity—involves the somewhat complex nature of the partnership. Most of the project falls within the Fanno Creek Greenway, owned and operated by the Tualatin Hills Park & Recreation District. There is also, however, a small amount of project acreage under private ownership. Metro, the regional government, is supporting the project with a $245,700 Nature in Neighborhoods grant, and Clean Water Services is handling the engineering, construction and revegetation.

 

The Transformation

The project team will re-establish the natural flow of Fanno Creek in the northern portion of the site, replace two undersized culverts with a pedestrian bridge, remove the berm surrounding the pond, and establish native plant communities along the entire Denney-to-Hall reach. The construction portions of the project are slated for summer 2019. By the time the heavy equipment rumbles away, the creek’s path will more closely resemble the natural curves it once had, and its access to the floodplain will be improved. The expected results include better plant and wildlife habitat, reduced erosion, and a trail crossing that’s less prone to flooding.

Revegetation is expected to begin in the winter/spring of 2020. Thanks to earlier efforts, invasive vegetation is already largely under control. The revegetation plan will leverage the latest knowledge about how to reduce conflicts between beavers and people. Plants of little interest to beavers, such as spirea, will be planted near the trails, while beaver will be drawn to willow and food/building materials in more remote areas, where they are expected to create rich habitat by building dams.

With the Denney-to-Hall project at Fanno Creek Greenway, the ecologically enhanced portion of Fanno Creek is growing by more than half a mile—bringing the total Tree for All projects along this urban stream to more than 11 miles. Greenway Park and Englewood Park, home to Tree for All projects launched more than a decade ago, are immediately south of Denney-to-Hall. Other current and future Tree for All sites exist both upstream and downstream of Denney-to-Hall. Increasingly, hikers and cyclists—as well as fish and birds – are encountering a near-continuous stretch of healthy creek all the way from Highway 217 to the mainstem of the Tualatin River. It’s as if a ribbon of cleaner water and healthier habitat is unfurling in some of the most developed portions of Oregon’s Tualatin River Watershed.


Learn More

Check for summer 2019 trail closures: Watch for signs at trailheads, call 503.629.6305 or visit the Fanno Creek Greenway webpage.

Explore a segment of the Fanno Creek Trail, including the Denney-to-Hall portion, from the perspective of Access Recreation, which provides information to benefit hikers with disabilities.

Learn about Metro’s Nature in Neighborhoods grants, which have funded dozens of projects in the region, including Denney-to-Hall.


KEY PARTNERS