page_title: Columbia Slough
section_title: Fish and wildlife
hierarchical_section_title: Columbia Slough / Biology / Fish and wildlife
caption_attribution_description: Great Blue Heron, Phalacrocorax auritus, juvenile. Location: Anhinga Trail, Everglades National Park, Florida, United States
context_page_description: The Columbia Slough is a narrow waterway, about 19 miles long, in the floodplain of the Columbia River in the U.S. state of Oregon. From its source in the Portland suburb of Fairview, the Columbia Slough meanders west through Gresham and Portland to the Willamette River, about 1 mile from the Willamette's confluence with the Columbia. It is a remnant of the historic wetlands between the mouths of the Sandy River to the east and the Willamette River to the west. Levees surround much of the main slough as well as many side sloughs, detached sloughs, and nearby lakes. Drainage district employees control water flows with pumps and floodgates. Tidal fluctuations cause reverse flow on the lower slough.
  The Columbia floodplain, formed by geologic processes including lava flows, volcanic eruptions, and the Missoula Floods, is part of the Portland Basin, which extends across the Columbia River from Multnomah County, Oregon, into Clark County, Washington. Five percent of Oregon's population, about 158,000 people, live in the slough watershed of about 51 square miles. Municipal wells near the upper slough provide supplemental drinking water to Portland and nearby cities.
context_section_description: Although reduced and altered, habitats in the watershed support a wide range of wildlife, some of which is found nowhere else in Portland. Many species that used the slough in 1850 still use it. This includes more than 150 species of birds, 26 species of fish of which 12 species are native several kinds of amphibians, western pond turtles, beaver, muskrat, river otter, and black-tailed deer. Juvenile salmon enter the lower slough as well as Smith and Bybee Lakes. Coastal cutthroat trout inhabit Fairview Creek and Osborn Creek. Three species of native freshwater mussel live in the slough and in Smith and Bybee Lakes. Crayfish have been found throughout the slough. Bald eagles are among the resident birds, and great blue herons have established rookeries in the watershed. Migrants that visit the slough include more than a dozen species of ducks, geese, swans, and raptors, as well as neotropical shorebirds and songbirds. Invasive species adapted to the slough include the nutria, common carp, bullfrog, and European starling.
caption: Great blue heron. These wading birds have rookeries in the slough watershed.
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