Oaks Bottom Tidal Restoration Project

By Don MacGillivray

Oaks Bottom is one of the few natural areas remaining along the Willamette River area in the Portland region. Probably the largest and most complex natural area within the City of Portland, it sits on east bank of the Willamette River between the Ross Island and the Sellwood Bridges.

It is 170 acres of wetlands, meadows, and wooded areas and plays host to an extraordinary array of wildlife including salmon, amphibians, crustaceans, small mammals, and over 185 species of birds. Many of these are considered “special status” because they are rare or in decline throughout Oregon.

Hikers can visit Oaks Bottom by using the trail beginning at Sellwood Park and ending at the Tadpole Pond. It is an easy, all season, family friendly, 3.8 mile loop with only about a 100 foot rise in elevation.

A restoration project will take place there this summer involving the enhancement of forty percent of the Oaks Bottom wetland habitat. It will especially benefit the public use of the area and improve habitat for the nearby wildlife.

The “Oaks Bottom Tidal Restoration Project” is being carried out by the City of Portland Bureau of Environmental Service and the United States Army Corp of Engineers, in partnership with the Lower Columbia Estuary Partnership, and the United States Fish and Wildlife Service.

The largest part of the project is the replacement of an outdated culvert that is an impediment to the fish and the stream feeding the wetlands inside the natural area. A new larger box culvert will allow them to pass easily in and out from the Willamette River to the marshland.

Likewise, the water channels of the slough will be improved with appropriate habitats to help young salmon travel to and from their spawning grounds. It will make it usable for all the wildlife to traverse under the railroad and the trail at all times of the year. It is part of the cities salmon recovery program to help restore the natural ebb and flow of water in and out of Oaks Bottom.

In addition to the culvert, there will be an extensive ecosystem restoration to improve the habitat of the birds and other small animals in the area. The Springwater Trail in Oaks Bottom will be closed to bicycles and pedestrians for up to four months this summer. Users will need to detour around the project, however access will be maintained to the Oaks Amusement Park and the Oregon Yacht Club.

At the completion of the project, two new wildlife viewing platforms will improve the public enjoyment of the area. There are many invasive vegetative species that will be removed and replaced with native plants to improve wildlife habitat.

All this work and other features will enhance the opportunity for the public to learn more about the importance of Oaks Bottom though hands-on environmental education and interpretation.

Before its rescue, this area was a landfill site destined to be used for industrial development. It became a wildlife park in 1969. Since then there have been several efforts to reclaim the area both for its natural flora and fauna as well as a place for Portlanders to experience the great outdoors in its natural beauty while still within the inner city.

The river’s ebb and flow is a major source of water in the lake and wetlands. The wetlands is fed by springs located at the base of the nearby bluff. Near the river is an early trolley line that was operated by the Portland Traction Company streetcar line. It parallels the hiking trail that is a section of the Springwater Corridor.

The Audubon Society, Nature Conservancy, Sierra Club, and the Sellwood-Moreland Improvement League were the primary advocates for retaining and improving this area as a natural wildlife sanctuary. It was designated as Portland’s first migratory bird park in 1988 and the Portland City Council adopted the Oaks Bottom Coordinated Resource Management Plan, which laid out a variety of objectives for its future management.

Oaks Bottom was always a natural area that needed improvement to make it welcoming to the public. While is was generally left alone, there were variety of abuses to the area that required attention before greater public access could be allowed. A project in 2012 included restoration work, and re-creating a walkway along the original trail with three new boardwalks, one with a deck overlooking the wetland area.

An extensive collection of wildlife frequents Oaks Bottom in the wooded areas around the marshlands. It is a birdwatcher’s paradise with more than 185 species including Canada geese, bald eagles, peregrine falcons, red-tailed and Cooper’s hawks, osprey, falcons, gulls, terns, hummingbirds, woodpeckers, quail, kingfishers, grebes, and many others.

Various types of ducks can frequently be seen too – mallards, pintails, wigeons, and green-winged teals. Portland’s city bird, the Great Blue Heron, nests on the nearby Ross Island.

The abundant wildlife living in the area includes beavers, river otters, muskrats, raccoons, and even deer and bobcats occasionally found in the park. The trees include Oregon white oak, Pacific madrone, cedars, maples, dogwoods, white alders, Oregon ash, black locust trees, cottonwoods and others.

There are still a variety of problematic and invasive species and work continues to physically remove them from the area. Care should be taken to avoid the poison oak that is along the trail and in the wooded areas.

High on the northeastern bluff overlooking Oaks Bottoms’ natural beauty is the Portland Memorial Mausoleum. On it’s western wall is a seventy foot, 45,000 square foot mural that honors the Great Blue Heron and the birds nearby. It is thought to be the largest hand painted mural in the United States.

This great educational feature depicts a variety of native wildlife. Hikers and children can use it to help identify wildlife found below.

The Oaks Bottom Wildlife Refuge will become an increasingly popular public destination and it has a secure future as one of the region’s significant urban wildlife and nature-viewing areas.

Oaks Bottom Tidal Restoration Project

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