Columbia Slough- What Is It?

(Columbia Slough on Bike Bridge Near the Wastewater Treatment Plant)

Whenever I move to a new area, I immediately seek out the nature spots nearby, and best places to walk my dogs. When I moved to Portland OR., and started exploring my neighborhood, I stumbled upon the nature reserve on Columbia Boulevard next to the water & sewage treatment facility. It seems a little odd to create an outdoor oasis next to a sewage treatment plant, but it really is a beautiful area close to my home that I can walk the dogs and feel like I’m in a pocket of nature, (despite the occasional unpleasant odor on certain days). A bike trail in this area travels  out to Marine Drive in one direction, or Smith and Bybee Lakes , and Kelley Point Park in the other.

During my first visit, I was stumped by the body of water that flowed through the area. It was too small to be the Columbia River, and larger than a runoff stream. Because of it’s close proximity to the water treatment facility, I honestly thought it was some sort of man-made  toxic runoff  from the plant, despite the fact that I could see evidence of life thriving in the area, (plenty of wildlife and foliage).  I later found out that this body of water is the Columbia Slough. I wasn’t familiar with the term “slough,” further cementing the idea that it had something to do with sewage waste water (“slough” just sounds so yucky).

However, my recent volunteer work with the Columbia Slough Watershed Council (CSWC) has taught me that the Columbia Slough is not man-made, is not part of the sewage treatment facility, and is a very natural occurring body of water influenced by the Columbia River.  The term “slough” is simply a body of water that is low flow, or stagnant, not necessarily “dirty,” although I will share environmental concerns below. The Columbia Slough travels through lakes and wetlands, and is in an area that used to completely flood every year, prior to human intervention.

The Slough is approximately 18 miles long with the headwaters at Fairview Lake in East Multnomah County. Traveling through Northeast and North Portland, (paralleling the Columbia River), the slough eventually flows into the Willamette River in Kelley Point Park.

-Columbia Slough Entering Willamette River in Kelley Point Park-

According to the CSWC website, the entire Columbia Slough Watershed contains 32,700 acres, 6 lakes, 3 ponds and 50 miles of waterway. The area has 26 identified fish species, 175 bird species and contains several wildlife corridors.

(Natural area near Columbia Blvd. Wastewater Treatment Plant)

Despite these amazing characteristics, many challenges are present in maintaining a healthy waterway, especially in this area. The Columbia Slough watershed is heavily industrial and residential, with approximately 158,000 residents-(1/20 of Oregon’s population), 54 schools, 2 universities, 1 community college, and 3,900 businesses, including Portland International airport and port of Portland marine terminals.

The Columbia Slough Watershed is made up of 54% impervious surfaces – solid surfaces where water can’t sink into the ground, and join under-ground water systems. Therefore, water runs along these surfaces such as sidewalks, streets, parking lots etc., picking up sediments, toxins, litter, and oil along the way. This contaminated water makes its way to the slough, where it travels to the Willamette River, onward toward the Columbia, and eventually out to the Pacific Ocean.

Unfortunately, storm water is only one source of pollution in the Columbia Slough. Failing septic systems, illegal dumping, and industrial equipment cleaning, all pollute the water systems as well.  Although the Slough has a long history of contamination, according to the Columbia Slough Watershed website, its cleaner today than it has been in the last 100 years due to great efforts made by the CSWC, and the surrounding community.

To read more about the Columbia Slough Watershed, flood history, and flood control levees, read my blog post Columbia Slough II.

Do you have an interesting story about your local waterways? Please share below!

Special Thanks to the Columbia Slough Watershed Council for all the environmental education, stewardship awareness, restoration, and relationship building they perform in the community and watershed. Much of the statistics I provided above I found on their website. Please visit the site for additional information, volunteer opportunities, and announcements for events and workshops.