Nature's "Drainage Canal": the
Columbia River Floodplain

   Although the Columbia Slough is 18 miles long, its watershed covers a 61 square mile area from urban North Portland to Gresham. Prior to human manipulation, the slough's channels, lakes, and wetlands absorbed the waters of the Columbia during natural periodic spring freshets and floods. The teeming plant and animal life, and rich soils of the floodplain drew human settlement to the area.

This 1909 postcard shows the Columbia Slough connected to the Sandy and Columbia Rivers during high water. The spring flood stage sometimes created a passage way on the slough from the Sandy River inland to the Willamette. Indians navigated the waterways of the sloughs and lakes near the Columbia, traveling to Willamette Falls. White settlers and East Portland residents also traversed the slough's waters. Courtesy of Nancy Hoover

  For centuries humans used the natural bounty of the Columbia floodplain. Over the past 150 years, they transformed the once-bountiful wetlands by logging, diking, and building levees.