Columbia River

About the Columbia River: Bonneville Dam to the Pacific Ocean

Astoria Bridge
Astoria Bridge near the mouth of the Columbia River.

The lower portion of the Columbia River stretches 146 miles from Bonneville Dam - the last of 14 dams on the river - to the Pacific Ocean. Another large tributary, the Willamette River, joins the Columbia downstream from Bonneville. When the Columbia finally meets the ocean more than 1,200 miles from its source in the Canadian Rockies, it flows in with such force that it spills a plume of freshwater four miles out into the ocean, creating an estuary of vital importance to people and wildlife.

Below are summaries of key EPA projects in the lower portion of the Columbia River basin.

Portland Harbor Superfund Site

The Portland Harbor Superfund site in Portland, Oregon, is the result of more than a century of industrial use along the Willamette River. Sediment is contaminated with many hazardous substances, including heavy metals, polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAH), dioxin, and pesticides. The cleanup investigation currently extends from the Columbia Slough to the Fremont Bridge.


Cleanup Progress in the Lower Columbia

Since 2006, 63 acres of contaminated sediments in the Lower Columbia River have been cleaned up as a result of state and federal actions. These 63 acres are among 400 acres of known contaminated sites in the Columbia River Basin.

Key cleanup sites include:

  • Ross Island, Portland (near mile 15 of the Willamette River)
  • Johnson Lake, Portland (south of the Columbia Slough)
  • ALCOA aluminum smelter, Vancouver, Washington

The cleanups in these areas provide a significant contribution to reducing toxics in the Columbia River.


Lower Columbia River Estuary Partnership

The Lower Columbia River Estuary Partnership is one of 28 programs in EPA's National Estuary Program (NEP) to protect and restore estuaries of national significance. The Partnership is a public-private initiative that cuts across political boundaries - integrating 28 cities, 9 counties, and the states of Oregon and Washington over an area that stretches 146 miles from Bonneville Dam to the Pacific Ocean. It's mission is to protect and restore the lower Columbia River estuary with on-the-ground improvements and education and information programs.