Lower Willamette River Floodplain – Oregon Conservation Strategy

The Willamette River mainstem from the confluence with the Columbia River (RM 0) upstream to Willamette Falls in Oregon City (RM26), its floodplain and adjacent uplands.

COA ID: 059

Recommended Conservation Actions

Improve aquatic and riparian habitat complexity and diversity.
Improve riparian buffers.
Maintain and enhance isolated wetlands to provide habitat for amphibians and turtles.
Maintain and expand Oregon white oak habitat
Protect and improve water quality.
Protect and restore shallow water and off-channel habitats.
Remove fish and wildlife passage barriers.
Restore floodplain function and connectivity.
Restore riparian and wetland plant communities.

Local Conservation Actions and Plans

Potential Partners

Special Features

General

Important movement corridor for migratory and resident fish and wildlife
Restoration of the Lower Willamette River and associated floodplain and uplands has important implications not only for fish and wildlife, but also for the social and economic factors resulting from restoring ecological functions such as flood control and water quality.
This area includes numerous important habitat sites including Oaks Bottom Wildlife Refuge and the confluence with the Clackamas River.

Previously Associated With

2006 COA ID CR-09 (Portland's Forest Park)
2006 COA ID WV-01 (Columbia River Bottomlands)
2006 COA ID WV-03 (Willamette River Floodplain)

Protected Areas

Bell View Point
Bluff above Swan Island
Butterfly Park
Camassia Preserve
Cathedral Park
Cedar Island
Cedaroak Boat Ramp
Clackamette Park
Cottonwood Bay
Dahl Beach
Dogwood Park
Elk Rock Island
Foothills Park
Forest Park
George Rogers Park
Glenmorrie Greenway
Goat Island
Gov. Tom McCall Waterfront Park
Harbor View Property
Holgate Slough
Japanese American Historical Plaza
Johns Community Garden
Jon Storm Park
Kelley Point Park
Kincaid Curlicue Corridor
Kingsley Park
Linnton Park
Maddax Woods
Mary S. Young State Recreation Area
McCarthy Park
McLean House
McLoughlin House
McLoughlin Promenade
Meldrum Bar Park
Mill Ends Park
Milwaukie Riverfront Park Property
Oaks Bottom Wildlife Refuge
Old Canemah Park
Oswego Creek Outlet Access Willamette River Greenway
Peter Kerr Property
Portland Classical Chinese Garden
Powers Marine Park
River Cover Open Space
Rivervilla Park
Robinwood Open Space
Rocky Island Park
Roehr Park
Ross Island Natural Area
Sellwood Riverfront Park
Smith And Bybee Wetlands Natural Area
South Waterfront Park

Ecoregions

Coast Range

Oregon’s Coast Range, known for its dramatic scenery, is extremely diverse, with habitats ranging from open sandy dunes to lush forests and from tidepools to headwater streams. It follows the coastline and extends east through coastal forest to the border of the Willamette Valley and Klamath Mountains ecoregions

Willamette Valley

The Willamette Valley ecoregion is bounded on the west by the Coast Range and on the east by the Cascade Range. This long mostly level alluvial plain has some scattered areas of low basalt, and contrasts with productive farmland and large urban areas. It has the fastest-growing human population in the state resulting in challenges due to land-use changes.

Strategy Habitats

Natural Lakes

Natural lakes are relatively large bodies of freshwater surrounded by land. For the purposes of the Conservation Strategy, natural lakes are defined as standing water bodies larger than 20 acres, including some seasonal lakes.

Oak Woodlands

Oak woodlands are characterized by an open canopy dominated by Oregon white oak.

Flowing Water and Riparian Habitats

Flowing Water and Riparian Habitats include all naturally occurring flowing freshwater streams and rivers throughout Oregon as well as the adjacent riparian habitat.

Ducks on a wetland in Ladd Marsh Wildlife Area, Oregon

Wetlands

Wetlands are covered with water during all or part of the year. Permanently wet habitats include backwater sloughs, oxbow lakes, and marshes, while seasonally wet habitats include seasonal ponds, vernal pools, and wet prairies.

Specialized Local Habitats

Basalt cliffs
bottomland hardwood forest
bottomland hardwood forest
Off-channel habitat
Riverine islands (Ross Island, Elk Rock Island, Rock Island, Cedar Island, Clackamette Island)
Shoreline and sandy beaches

Strategy Species

Acorn Woodpecker (Observed)

Melanerpes formicivorus

California Myotis (Modeled Habitat)

Myotis californicus

Cascade Torrent Salamander (Modeled Habitat)

Rhyacotriton cascadae

Chinook Salmon (Documented)

Oncorhynchus tshawytscha

Chipping Sparrow (Observed)

Spizella passerina

Clouded Salamander (Modeled Habitat)

Aneides ferreus

Coastal Cutthroat Trout (Documented)

Oncorhynchus clarki clarki

Coho Salmon (Documented)

Oncorhynchus kisutch

Common Nighthawk (Observed)

Chordeiles minor

Fringed Myotis (Modeled Habitat)

Myotis thysanodes

Hoary Bat (Modeled Habitat)

Lasiurus cinereus

Lewis’s Woodpecker (Observed)

Melanerpes lewis

Northern Red-legged Frog (Observed)

Rana aurora

Northern Spotted Owl (Observed)

Strix occidentalis caurina

Olive-sided Flycatcher (Observed)

Contopus cooperi

Oregon Slender Salamander (Observed)

Batrachoseps wrighti

Oregon Vesper Sparrow (Observed)

Pooecetes gramineus affinis

Short-eared Owl (Modeled Habitat)

Asio flammeus flammeus

Silver-haired Bat (Observed)

Lasionycteris noctivagans

Steelhead / Rainbow / Redband Trout (Documented)

Oncorhynchus mykiss ssp

Townsend’s Big-eared Bat (Observed)

Corynorhinus townsendii

Western Bluebird (Observed)

Sialia mexicana

Western Gray Squirrel (Modeled Habitat)

Sciurus griseus

Western Meadowlark (Observed)

Sturnella neglecta

Western Painted Turtle (Observed)

Chrysemys picta bellii

Northwestern Pond Turtle (Observed)

Actinemys marmorata

Purple Martin (Observed)

Progne subis arboricola

Western Ridged Mussel (Observed)

Gonidea angulata

White Rock Larkspur (Observed)

Delphinium leucophaeum

White-breasted Nuthatch (Observed)

Sitta carolinensis aculeata

White-topped Aster (Observed)

Sericocarpus rigidus

Willow Flycatcher (Observed)

Empidonax traillii

Winged Floater Freshwater Mussel (Observed)

Anodonta nuttalliana

Yellow-breasted Chat (Observed)

Icteria virens auricollis

Strategy Spotlight: Willamette River Confluences

Confluences, the point where two or more river systems come together, are ecologically vital areas, especially along the Willamette River. Over the past two centuries, the Willamette River has been transformed from complex and dynamic system, to a much more simplified and largely channelized river. Throughout the Willamette Basin, there has been widespread loss of floodplain and off-channel habitat due to human encroachment onto the floodplain, physical barriers (such as rip-rap and revetments), loss of side channels, and changes in flow regimes that eliminate floodplain-inundating flows. These changes have significantly harmed Oregon’s native species, resulting in state and federal listings of several plant and wildlife species associated with the river and its floodplain.

Protection and restoration of channel complexity, riparian habitat and floodplain forest have been identified as critical conservation needs in the Willamette Ecoregion by multiple plans and programs, including the Upper Willamette River Conservation and Recovery Plan for Chinook Salmon and Steelhead, Oregon Conservation Strategy, Willamette Subbasin Plan, and Willamette River Floodplain Restoration Study Draft Integrated Feasibility Report/Environmental Assessment.

A partnership between three grant-making organizations – Meyer Memorial Trust, Oregon Watershed Enhancement Board (OWEB), and Bonneville Power Administration (BPA) – has been instrumental in addressing the complex issues facing the Willamette River floodplain. These funders work together to support one another’s objectives, while simultaneously pursuing their own mainstem agendas.

Spring 2014, before construction. Three deep, steep-sided, warm water former gravel extraction pits (ponds) disconnected from the Middle Fork Willamette River. Photo Credit: © RaptorViews Philip Bayles.

September 2014, after grading, contouring and sloping banks, connection to the Middle Fork Willamette River and installation of habitat structures was finished. Photo Credit: © RaptorViews Philip Bayles.

Significant support from this partnership has enabled non-profits, watershed councils, and soil and water conservation districts to increase the extent and pace of protection and restoration efforts along the Willamette River. Other significant partners working in this area include private landowners, Oregon Department of Fish and Wildlife, Oregon State Parks, and the U.S. Army Corps of Engineers.

In 2010, The Nature Conservancy (TNC), with significant help from BPA and OWEB acquired the 1,271-acre Willamette Confluence Preserve. Historically, the property was used for a floodplain gravel mining operation, with extraction actively occurring from the 1950s through the 1980s. As a result, the floodplain became disconnected from the river by levees designed to protect the gravel pits. Although portions of the property were significantly altered, an intact floodplain forest remained, which is a limiting feature throughout most of the low-gradient portions of the Willamette Basin.

In 2014, TNC, with funding from the NOAA Restoration Center, OWEB (includes funding from the Pacific Coast Salmon Recovery Fund), Meyer Memorial Trust, Bonneville Environmental Foundation, and others completed an extensive restoration project to increase the amount and quality of floodplain and off-channel habitat and improve water quality. The project reconnects the Willamette River to its floodplain, creates new river channels and increases and improves shoreline habitats. A major goal of this work is to restore natural floodplain and in-channel habitat forming processes to provide critical juvenile rearing and adult holding habitat for native fish, including Chinook salmon.