About the Watershed

The Columbia Slough is a 60-mile remnant of lakes, wetlands, and slow-moving channels that were formerly floodplains connected to the Columbia River. The Slough wetlands and waterways were home to Native peoples for millennia, namely the Upper Chinook. The Slough provided abundant and diverse fishing and hunting opportunities, and safe canoe passage. Today, the ceded land now known as Portland is home to the nation’s ninth largest urban Native American population.



The Portland metro area rests on traditional village sites of the Multnomah, Kathlamet, Clackamas, Chinook, Tualatin Kalapuya, Molalla. Longhouses with hundreds of residents stretched along the Slough in a village called Neerchokikoo. The Hudson’s Bay Company set-up camp across the water from the Slough--in present-day Vancouver--and began trapping otter and beaver in 1820.  Neerchokikoo villagers faced extremely difficult circumstances with the settlement of Portland, and the majority of tribal peoples were forcibly removed or died due to smallpox and other European diseases during the “cold sick” epidemic of the early 1830’s.  By the 1850’s, Europeans were rapidly settling the area, and farming had replaced trapping as the main European economic activity. Despite removal and disease, some Chinook tribal members continued to live along the Slough, with the last documented remaining elder moving out in 1906.

In the early 1920’s levees were constructed to prevent seasonal flooding and the waterway was transformed into the channeled and highly managed system now known as the Columbia Slough. With the elimination of yearly floods farming, industrial and residential development flourished.


Today the 40,000 acres of watershed contains 24,000 homes, 4,500 businesses, and is home to 1/10 of all the jobs in Multnomah County. Each year more than 13.7 million people and over 275,000 tons of freight come through the watershed. Impacts from 150 years of development have left a legacy of environmental problems in the Slough: contaminated fish and sediment, diminished wildlife habitat, and water pollution from both point and non-point sources. The Columbia Slough Watershed Council was formed to address these issues.


As habitats are modified throughout the Portland metropolitan region and the entire Northwest, the Slough’s importance as a component of our regional system of greenspaces grows. The Slough is one of the largest urban waterways contained wholly within the metropolitan urban growth boundary. This vast ribbon of habitat and openspace can be explored by foot, bicycle or canoe and kayak. Flanked on the west by the 2,000 acre Smith and Bybee lakes, and on the east by the 102 acre Fairview Lake and the headwaters of Fairview Creek near Grant Butte in Gresham, the 60 mile Slough and its watershed represent an irreplaceable resource, both for the region and for north and northeast Portland, Gresham, Fairview, Troutdale, and Wood Village.

Columbia Slough Watershed Facts

  • 32,700 acres

  • 175 bird species

  • 26 fish species

  • 6 lakes, 3 ponds, 50 total miles of waterways

  • Contains Smith and Bybee Wetlands, the largest urban wetland in the U.S.

  • Lower slough is a refuge for endangered salmon

  • Wildlife corridors

  • 30 miles of flood control levees

  • 170,000 residents

  • 4,200 businesses

  • 2 universities, one community college

  • ​Columbia South Shore Well Field-part of the City of Portland and City of Gresham’s drinking water

  • Critical transportation corridors-I-5, I-205, I-83, and Highway 30

  • 250,000 railroad cars pass through

  • Water quality listed under 303(d)

  • Six golf courses

  • 40 mile Loop Trail-trail system over 150 miles

  • Canoe and kayak launches

  • 60% impervious surfaces

  • Portland International Airport and Troutdale Airport

  • Portland Marine Terminals

Slough Access

Paddler's Access Guide to the Columbia Slough

Nature in the City Watershed Map


© 2020 by Columbia Slough Watershed Council