Beaver Creek is a small urban stream. It flows from unincorporated Multnomah County, through the City of Troutdale, and joins the lower Sandy River. Despite its small size, the stream is very important to the local river ecology. A study by Mt. Hood Community College students,
“This stream is surprisingly important when it comes to supporting endangered fish populations,” said Roy Iwai, Water Quality Program Manager for Multnomah County.
For over a decade, Iwai has worked with Multnomah County Roads and local partners to support the ecological restoration of Beaver Creek. Over that time, Iwai has led the effort to remove three major barriers to fish passage: Stark Street, Cochran Road, and Troutdale Road crossings. The barriers were a result of poorly designed culverts, outdated infrastructure, and the changing urban landscape.
Culverts are big metal pipes, or sometimes concrete boxes, that allow the stream to flow under a road. However, problems can arise because of a culvert's shape and size, if it was not originally designed to allow returning salmon to reach their spawning habitats. The stream may become constricted and flow too fast for fish to swim against, or the jump may be too high for a fish to enter the culvert. Logs and debris at the culvert inlet may eventually block returning adult salmon from swimming upstream to spawn. It can also be a barrier for juvenile salmon, as they swim downstream to the Columbia River, and finally, to the Pacific Ocean.
Iwai has worked with Mount Hood Community College (MHCC), located next to Beaver Creek, to study the impact of culvert removal projects. This collaboration has let students learn restoration ecology in a hands-on, local opportunity. Since replacing a failing culvert with a modern bridge, Iwai and MHCC students and professors continue to monitor how the stream changes over time.
A Messy River is A Healthy River
When the culvert was replaced with a bridge, it allowed for more natural stream flows. One surprise was a much more messy stream channel upstream of the culvert replacement.
Streams with fallen logs and deep pools are better for fish and other wildlife. When a stream is straight and fast-moving, adult fish may not have good places to build their “redds” (pockets of gravels to lay eggs), and juvenile fish that emerge from eggs in the gravel don’t have a place to hide from predators, rest, and grow. “What might look messy or chaotic to us, is actually a healthy habitat for fish,” said Iwai. “You want to see a braided network of side channels, woody debris, pools, riffles, and overhanging shade trees to ensure fish have what they need to thrive.”
A major culvert replacement in 2017 has led to a much healthier stream, according to a recent analysis by MHCC students. MHCC Natural Resources Technology Program students, including Jake Kerslake, Sara Martin, and Joel Campean, recently completed their class project to study the changes in channel morphology in Beaver Creek. Since the completion of the County's Stark Street culvert replacement project in 2017, the stream has flowed naturally without the constriction experienced at the old culvert. Using the field measurement techniques they learned in class, the students recorded new stream cross-sections in Beaver Creek. Their exploration using aerial photos of the Beaver Creek channel from 2003-2007 shows us how the stream has changed over time. From a single confined channel, the stream has quickly evolved into a more complex meandering and braided channel form with a diverse instream habitat. The new pools and riffles support juvenile salmon and resident trout. Read their full report.
The results show that focused and coordinated efforts can help urban ecosystems recover and thrive. The work of restoring Beaver Creek has included many partners over the years, including the East Multnomah Soil and Conservation District, Oregon Metro, SOLVE, the City of Gresham, the City of Troutdale, the Oregon Department of Fish & Wildlife, and others.
One Last Challenge
The third major barrier for salmon migrating upstream in Beaver Creek is the Troutdale Road Culvert. The County was recently awarded a federal grant to fund this project, and construction is expected to begin in 2027.
This 1930s culvert was built when Troutdale was all farmland. Now with urban storm water, the culvert is too small. It was retrofitted with a fish ladder by the Oregon Department of Fish and Wildlife in the 1950s, but over time that fish ladder is beginning to fail. The new structure will be a bridge, allowing the stream and logs to flow naturally under it. The Troutdale Road culvert is downstream from the Cochran Road and Stark Street fish barrier removal projects and is vital to ensuring that the six miles of habitat are accessible to migrating fish. “The replacement of this Culvert will be good for fish and human habitat,” said Iwai, “because it will include new sidewalks and bicycle lanes on this segment of Troutdale Road. This section of roadway will be safer and climate resistant, while also opening up habitat for fish."
