City of Lake Oswego: Engineering: Environmental Services

The Engineering Division consolidates the engineering functions of the water, sanitary sewer, and surface water utilities as well as development engineering and solid waste and recycling. We are committed to excellence in infrastructure management, planning, design and construction. We cover a wide range of activities including the Willamette Shore Trolley, Pathways, the Transportation Advisory Board, the traffic count program, the sponsor a bench program, the Neighborhood Traffic Management Program, as well as general transportation related issues. We also provide spatial information to both internal and external customers by producing maps, atlases, aerial photos and construction plans.

During recent winter storms, the City of Lake Oswego experienced limited instances of sanitary sewer overflows. Unusually heavy sustained rains led to infiltration of groundwater into sanitary sewer lines exceeding their available capacity.

The Oregon Department of Environmental Quality advises that residents who plan to use the lake for in-water recreation this winter should take the same precautions that they would normally take. While the diluted flows may have carried some bacteria, it is reasonable to assume that it has since dissipated through further dilution and cooler temperatures. It is generally good advice to avoid ingesting the water and shower/clean thoroughly after being in the lake.

Unusually heavy rainfall has certainly challenged the system this winter, and there are efforts underway to address capacity and durability of our infrastructure through a combination of temporary measures, ongoing maintenance, and long-term improvements.

Until the main sewer interceptor is replaced, heavy rain and the prediction of more rain can trigger sewer overflows in the lake interceptor pipe and the sewer trunk lines leading to the interceptor.

To reduce the frequency, duration and amount of sewer overflows the City developed an Overflow Response Plan (ORP) to protect public health.

Maintenance Services staff will be activated to immediately deploy to the location of the first point of overflow in the system.
Nearby points of inflow to the stormwater system will be blocked and a containment area set up to vacuum wastewater overflow before it reaches the lake or storm
Access to any potential areas of overflow will be restricted to ensure public safety.

In the event of a large spill that can not be contained, sewage may flow into the BlueHeron Canal. Please do not come into contact with the canal or lake waters until you are notified that it is safe to do so. Please prevent your pets from swimming in or drinking from these water bodies.

The city’s goal is to prevent spills whenever possible. If you see discolored water coming from a manhole, please call Maintenance Services or 911 at the phone numbers below.