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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

More Contact Info

Odor Notification

Sewer Odors Reported: November 17, 2021

The Columbia Boulevard Wastewater Treatment Plant treats wastewater from Portland homes, businesses, and industries. This important facility protects public health and the environment and makes our community more livable. We work hard to be a good neighbor in North Portland, to give Portland sewer ratepayers the best value for their rate dollars, and to meet the highest operating standards.

Over the last month, neighbors near the Columbia Boulevard Wastewater Treatment Plant have submitted an unusually large number of odor reports. Most reports came from neighbors who live or work within a couple miles of the plant. We investigate every odor report we receive to determine the source.  In some cases, we find that the treatment plant or other bureau facilities (like storm drains or manholes) are the source of the odors.

Recently, neighbors have reported a strong sewer odor coming from the sewer system as far as one mile south and two miles east of the plant in North Portland. We are investigating this issue but have not yet confirmed the source. We have early indications that the odor may be due to an emergency project where a force main (a pressurized sewer) has been temporarily connected to a sewer main. The force main has stronger sanitary sewer flows than a typical sewer pipe. This may be pushing odors further out into the neighboring sewer pipes where they escape from storm drains.

What happens next?

Environmental Services is continuing to investigate.  If we determine that one of our facilities or projects is the source, we will take steps to address and mitigate the odor. We will send another notice when we confirm the source of the odors.

How can you help?

Please help us with this investigation by continuing to report sewer odors. Call 503-823-1700 or submitting an online report at

Health concerns

Some neighbors have expressed concerns regarding whether the sewer odors are hazardous to public health. Sewer gases (methane, H2S, etc.) in an enclosed pipe can be hazardous to humans, but once these gases escape and hit the outside atmosphere, they diffuse rapidly. Sewer odors are considered a nuisance at the levels typically associated with public sewer systems, and do not pose a hazard to public health. Crews will be monitoring H2S levels at reported locations.

You can find out more about information about odor investigations at

For more information

If you have questions or would like more information, please contact Debbie Caselton by email at or by phone at 503-823-2831. If you want to report a sewer odor, please call 503-823-1700 or submit a report online at


Odor Notification Alert: April 22, 2021

We are taking aeration basin #8 out of service for cleaning then a new wall coating will be applied to the basin walls as part of our ongoing maintenance program. The basin will be offline from April 23 through August 6 while we are cleaning, performing repairs and upgrades. While we take aeration basin #8 out of service, there is a possibility for odors to be produced. While we don’t anticipate these odors to be perceptible outside our campus, this is a possibility until the cleaning is complete. We know these odors can be unpleasant and we make every effort to reduce them.

Odors produced from the collection system and wastewater treatment plant are captured and treated through a variety of processes. Occasionally, maintenance activities will hinder our ability the capture and treat these odors, allowing them to be perceptible in surrounding neighborhoods. Environmental Services issues notification regarding these maintenance projects that may result in odors outside our campus boundaries.

Odor Notification Alert: August 14, 2020 update September 2, 2020

On August 11 we discovered a sinkhole at the front of the plant. We investigated and determined a sewer line that brings sewage into the plant for treatment has collapsed.  A contractor was brought in under an emergency contract to expedite the repairs. A temporary line was put in on the east side of the campus to convey the sewage from the Inverness Force main to the Columbia Slough Consolidated Conduit and then to the treatment plant. We expect the repair work to take about two months. We will continue to update as we work to repair the line.  

The collapsed line damaged an isolation gate and is allowing odors to be migrate around the collapsed line. The contractor has covered the exposed line to prevent these odors from being released. The line will need to be uncovered to repair the gate and replace the line. During these activities odors can be released into the air without odor treatment. While we don’t expect these odors to be noticeable outside our campus, this is a possibility until the work is complete, especially in warmer temperatures. We know these odors can be unpleasant and we make every effort to reduce them.

Odors produced from the collection system and wastewater treatment plant are captured and treated through a variety of processes. Occasionally, maintenance activities will hinder our ability the capture and treat these odors, allowing them to be perceptible in surrounding neighborhoods. Environmental Services issues notification regarding these maintenance projects that may result in odors outside our campus boundaries.

How to Report Odors

How to Get Odor Information

Subscribe to odor notification email

Click here to receive odor alerts by email

Go to the online odor report form

Fill out and submit this form online to let us know about odor problems

Tour The Treatment Plant

Request a tour of the Columbia Blvd Wastewater Treatment Plant.