Lake Oswego Tigard Water Treatment Plant

A large plant modernization and expansion in a suburban neighborhood, the Lake Oswego Tigard Water Treatment plant features 11 new buildings that replace a 1960’s vintage plant. The sustainable and seismically resilient treatment plant expansion triples the plant capacity within a limited footprint using new technologies, including high rate clarification, biological filters, and new solids facilities.



West Linn, OR


City of Lake Oswego


Slayden Construction






2018 DJC Top Projects, First Place, Infrastructure Award

2018 Excellence in Engineering Award, Best Large Category Project, American Water Works Association (AWWA) / Pacific Northwest Section (PNWS)

2018 Excellence in Concrete, Utility Award, OCAPA/ACI


Thomas Harris, Photos
GreenWorks, Watercolor

Facing challenges ranging from community opposition to adverse soil conditions, the city relied on MWA to site and design buildings providing a contextual neighborhood interface at plant edges, and consolidating more industrial process facilities to the center of the property. MWA and MWH produced a Good Neighbor Plan which included many public and one-on-one meetings listening to neighbors in order to address concerns with this plant expansion in the quiet residential area.

Park-like amenities include public access, walking trails and lush landscaping

Serving as the public face for the facility, the administration, operations, and laboratory building is the main plant entrance for visitors and staff.

The exterior makes use of a natural palette of brick, wood, and Swisspearl accents.

Generous views of the wooded surroundings are provided for staff and plant operators

Process facilities like the finished water pump station are designed for both function and operator comfort and provide ample natural light through use of windows and skylights


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