Skip to Article Set Weather Back To Main Menu Close Customize Your Weather Set Your Location: Enter City and State or Zip Code Submit Subscribe now Account Menu Sign in Chevron that denotes content that can open up. Create account Chevron that denotes content that can open up. Newsletters Help/FAQ Search Please support high-quality local journalism. Subscribe to OregonLive. Portland Updated Jan 09, 2019; Posted Jul 06, 2016 Moore Island and Columbia Slough 15 Gallery: Moore Island and Columbia Slough Facebook Share Twitter Share By Lizzy Acker | The Oregonian/OregonLive The Columbia Slough is a 19-mile-long waterway, the remnant of an old wetland, controlled by floodgates and pumps, and it runs from near the confluence of the Columbia and Willamette in between the two rivers, past golf courses, freight yards and Portland International Raceway. Great blue herons and great ...