A Popular Trail, a Healthy Creek

Gales Creek is one of the Tualatin River’s major tributaries, and Forest Grove’s B Street Trail is one of the major points where people access Gales Creek. Erosion can be a significant problem at this location, as is the meagre presence of native vegetation. In the summer of 2019, partners are launching a three-year enhancement project just upstream of the B St Trail Bridge that will improve creek stability, water quality, and wildlife habitat. The project is designed to reconnect the creek and the floodplain without increasing flood risk for the adjacent demonstration farm.


The Site

First planting: 2008 (entire Natural Area); 2019 (current project)
Size: 3 acres
Stream length: 175 feet
Plant communities: Riparian Forest

 

The Challenge

This small site is home to many challenging features, including two earthen berms and the remnants of a railroad trestle. The berms, built long ago for flood control, don’t protect the adjacent road or farm from flooding in extremely high water events. They do, however, disconnect the creek from its floodplain, to the ecological detriment of both. The remnant trestle, meanwhile, functions only to accelerate erosion in the creek. In many spots, the creek banks are exceedingly steep, with little-to-no vegetation to stabilize the banks or cool the water below. What’s more, any stream enhancement activity in this area needs to avoid increasing the flood risk for the human infrastructure that flanks the site: A popular trail with a pedestrian bridge; a major road; and a teaching farm operated by Pacific University as a demonstration site for sustainability initiatives.  

 

The Transformation

This site is part of the larger Gales Creek Forest Grove Natural Area, where Tree for All partners have been active for more than a decade. Now, Metro, Clean Water Services and the City of Forest Grove, have come together to plan a three-phase, three-year project that will improve water quality, creek stability, wildlife habitat, plant communities and recreational opportunities along this particular reach of Gales Creek, just off the B St Trail.

Phase 1, Summer 2019: Construction crews will remove the remnant railroad trestle; rebuild the creekbank to slope more gently and connect with the floodplain; and place large woody debris (habitat logs) along the channel and below the creek's high water line. This phase will wrap up with the planting of thousands of native plants, which will help stabilize the creek, shade the water and create wildlife habitat.

To keep people safe during heavy construction, Phase 1 will involve several brief closures of the B St trailhead, as well as a temporary closure the entire B St Trail. The Old Town Loop and Highway 47 portions of the trail will remain open. The project team will reach out to trail users and neighbors to let them know about the trail closure, which is expected to last about two weeks, probably in August or September.

Phase 2, Summer 2020: Clean Water Services crews will build a shallow overflow swale that reconnects the creek on the right bank with its floodplain. Thousands of native wetland and riparian plants will be planted in this swale.

This phase also involves lowering a portion of the outer berm to floodplain elevation. During very high water events (typically 2-3 days/year), this floodplain reconnection is expected to result in two changes:

  • Water will move more slowly in the creek, decreasing erosion, and

  • Water will move through the full floodplain, improving ecological function in that area.

This project is not expected to increase the risk of flooding of human infrastructure, including the B Street farm and B Street itself. These areas do flood every decade or two, and the outer berm is not protecting them.

Phase 3, Summer 2021: After the plants have become established in the shallow swale, crews will remove a portion of the outer berm to let higher wintertime creek water flow into the swale from time to time. This phase will also include opportunities for volunteers from the Forest Grove and Pacific University communities to plant native trees and shrubs on the rest of the floodplain.

After these three phases are complete, partners will continue to monitor and manage the plants, creekbanks, habitat logs and other elements of the project for at least 20 years. The area is permanently protected as a public natural area.

This project will create habitat that helps to regulate temperature, sediments and nutrients on Gales Creek, home to some of the most important winter steelhead habitat in the entire Tualatin Valley. Thanks to the popular and growing network of trails, thousands of regional and local visitors will have an opportunity to experience the benefits of ecological enhancement, just steps from downtown Forest Grove and Pacific University. The Gales Creek Forest Grove Natural Area will become an even more valuable hands-on learning site for local students, from pre-K through Pacific University.  


KEY PARTNERS