Oaks Bottom Habitat Enhancement Project Overview
Environmental Services, Portland Parks & Recreation, and the U.S Army Corps of Engineers worked together on a large-scale habitat enhancement project to benefit wildlife and people. The project restored 75 acres of wetland habitat in 2018 by:
- Replacing an existing culvert with a larger culvert to make it possible for fish to pass between the Willamette River and the wetland refuge, as well as to improve the tidal flow of the Willamette River in and out of the refuge.
- Excavating tidal slough channels and improving wetland habitats so young fish, including species listed as threatened or endangered, can use the calmer waters of the wetland to rest and find food.
- Removing invasive vegetation, such as purple loosestrife, and revegetating with native species within the construction footprint.
- Enhancing opportunities for environmental education and interpretation of the refuge from the Springwater Trail with a new wildlife viewing platform and an overlook for people to observe nature.
Details of the project
WILL SALMON USE HABITAT IN THE WILDLIFE REFUGE?
Generally, when the right kind of habitat is available, it gets used. In Crystal Springs – when we removed barriers, salmon were immediately visible. We expect that salmon will immediately use the refuge now that they can get there. Salmon seek out cooler, calmer water, and the new channels are now ideal for baby salmon to hide from predators, find food, and rest. Because the habitat is primarily for young salmon on their way to the ocean, their presence may not be as visible. Environmental Services' scientists will regularly survey for fish. When we have news, we’ll share it!
THE SITE LOOKS BARE. WILL IT BE PLANTED?
In February 2019, Environmental Services' crews planted thousands of seedling- and cutting-sized trees and shrubs. The small-sized plantings will take a while to fill in, but eventually we expect that the entire project area to be covered with native vegetation.
WILL THIS PROJECT HELP CONTROL PURPLE LOOSESTRIFE?
With the water control structure gone and a better culvert installed, purple loosestrife may not thrive like it did. Time will tell. Parks and Environmental Services will continue to work with Oregon Department of Agriculture and other partners to control purple loosestrife in the refuge, while also continuing to work on establishing native vegetation in the refuge.
WHAT ARE THOSE SLASH PILES? WILL THOSE BE CLEANED UP?
As much as possible, vegetation that needed to be cleared was re-used on the site. Rather than haul excess woody material offsite, the contractor used the material to construct brush piles for birds, reptiles, salamanders, and small mammals to use for nesting and cover. Trees were also re-purposed as large woody debris in the channels.
WHAT IS THE DIFFERENCE BETWEEN THE VIEWING PLATFORM AND THE OVERLOOK?
Construction of the overlook is complete. It is the wide section of the trail near the new channels and culvert. The viewing platform will be an elevated, wood deck that will be constructed closer to Oaks Amusement Park and ideal for wildlife viewing in the refuge's open water area.
DID THE SPRINGWATER CORRIDOR TRAIL CLOSE DURING THE PROJECT?
The trail was open to the wildlife refuge but closed as a through route as crews cut through the trail, railroad tracks, and berm during construction. To better understand the construction process, check out the photos on our Flickr Page and a timelapse video of the construction.
More about Oaks Bottom
The Oaks Bottom Wildlife Refuge is a 170-acre complex of wetlands, shrublands, and woodlands on the east bank of the Willamette River just north of the Sellwood Bridge. The refuge is the largest remaining natural area within the lower Willamette River floodplain and provides important habitat for fish and wildlife, including threatened salmon and over 175 bird species. Oaks Bottom also supports many wildlife species that are considered “special status” because they are in decline on a regional or statewide scale. These include 44 bird species, three bat species and one amphibian species.
Portland Parks & Recreation manages the site as an important habitat area and an inviting place to enjoy wildlife viewing in the heart of the city. The Springwater Corridor, a portion of the region’s trail network, runs along the western edge of the refuge. A hiking trail and one hike/bike trail connect the refuge with two visitor parking lots and the Sellwood neighborhood to the east.
Portland Parks & Recreation created the city’s first wildlife refuge at Oaks Bottom in 1988 after a long history of environmental degradation at the site. Now Sellwood residents, schools and colleges, and groups such as Portland Audubon, the Urban Greenspaces Institute and Willamette Riverkeeper work with the city to restore habitats at the refuge.