Map of <a href="https://en.wikipedia.org/wiki/Columbia_Slough" class="extiw" title="en:Columbia Slough">Columbia Slough</a> watershed in Multnomah County, Oregon, United States. The slough begins in Fairview, Oregon, and flows into the <a href="https://en.wikipedia.org/wiki/Willamette_River" class="extiw" title="en:Willamette River">Willamette River</a> at Portland. The symbol P indicates a pumping station.
U.S. Census, Finetooth
Taken from U.S. Census website <a rel="nofollow" class="external text" href="http://factfinder.census.gov/home/saff/main.html?_lang=en">here</a> and modified by <a href="//commons.wikimedia.org/wiki/User:Finetooth" title="User:Finetooth">User:Finetooth</a>. Watershed boundaries from Portland Bureau of Environmental Services <a rel="nofollow" class="external text" href="http://www.portlandonline.com/bes/index.cfm?c=36082&amp;a=63594">here</a> and Columbia Slough Watershed Council <a rel="nofollow" class="external text" href="http://www.columbiaslough.org/images/maps/columbiaslough_general.gif">here</a>.