Lake Oswego's original water treatment plant (WTP) was built in 1968, treating Clackamas River water to drinking water standards for almost 50 years.

The initial treatment capacity was 10 million gallons per day (mgd), and later was expanded to 16 mgd in the 1980s. Even though the facility has been updated over the years, it was too old and undersized to meet the current and future demand in the area.

This project increased the plant capacity to 38 mgd and began supplying water to both Lake Oswego and Tigard in the summer of 2016. The new treatment plant produces high-qulaity drinking water using high rate, conventional sedimentation and filtration plus ozone technology, to assure a reliable and consistent supply of water for more than 90,000 customers.

This plant was designed to incorporate energy efficiency, renewable energy components, and sustainable operations. The facility is ablle to withstand large seismic events. It also ties in with the CIty of West Linn's system allowing the plant to serve as a back-up water source in case of an emergency.

Slayden's construction of this $69 million plant included upgrading the existing WTP from 16 to 38 mgd. The new replacement facilities were built on top of existing facilities in three phases. After completion of each phase, demolition of existing structures occurred to build te new facilities. All work was done while ensuring the existing plant stayed operational to produce clean water. The project included extensive yard piping and tie-ins, complex demolition, and electrical building, mechanical dewatering, and an administration building.