Oaks Bottom Wildlife Refuge, Wildlife refuge in Sellwood, Portland, US

Oaks Bottom Wildlife Refuge is a 141-acre city park in a floodplain on the east bank of the Willamette River near Sellwood, southeast Portland. It holds a shallow seasonal lake and wetland, open grass, and mixed maple and oak woodland. The Springwater Corridor path runs through it beside the Oregon Pacific Railway tracks on a berm, and a 1-mile trail wraps the lake's east side beneath a bluff topped by the Portland Memorial Mausoleum Mural, a great blue heron.

The rail line's raised bed largely cut the wetlands off from the Willamette River. The city acquired the south part of the wetlands in 1969 to prevent industrial development, and later filled the north end with debris from Interstate 405 construction. After years of debate, and pressure from the Audubon Society of Portland, the Sellwood-Moreland Improvement League and The Nature Conservancy, Oaks Bottom was designated Portland's first urban wildlife refuge in 1988.

Volunteers from Friends of Oaks Bottom have maintained trails, restored habitat and run information services since the 1988 designation. The name comes from the Oregon white oaks on the slopes above the wetland. Portland Memorial Mausoleum, on the bluff east of the lake, carries a large great blue heron mural facing the refuge.

You can enter through Sellwood Park's parking lot and walk several trails including the 2-mile Bluff Trail that connects to the larger Springwater Corridor path system. Early morning and dusk hours offer the best chances to see and hear wildlife, so plan your visit accordingly for better observation.

Beavers have repeatedly dammed the small stream linking the lake to the Willamette, working against the parks department's water-level plan. Staff countered by running a perforated pipe through the beaver dam, so water still flows. Boards added or removed at a small dam near the railway berm regulate the wetland, mimicking conditions from when it was fully connected to the river.