Project Overview

What is the Lake Oswego Interceptor Sewer?

Constructed in the early 1960's, the Lake Oswego Interceptor Sewer lies submerged some 14 to 21 feet below the surface of Lake Oswego. The LOIS system includes over 13,000 feet of 16 to 36-inch diameter pipe traversing Lake Oswego and over 5,000 feet of smaller diameter trunk sewers constructed through canals and bays. Today, the LOIS system collects flows from a 4,500 acre service area and transports these flows down to the City of Portland's Tryon Creek Wastewater Treatment Plant (TCWTP) by gravity, where it is then treated and discharged to the Willamette River. While some of the pipe is buried, nearly 9,000 feet is pile-supported above the lake bed to maintain a uniform slope to the treatment plant. About 40 manholes are scattered across the lake, canals and bays to provide access for maintenance and inspection. The LOIS system has two major deficiencies that must be addressed: capacity and structural soundness of the pile-supports.

Overview contents	More information
What is the problem? How did the City assess the problem? Exploring In-Lake versus Around-the-Lake options Project Finance LOIS Service Area How Will the New System Work? System Components Kelok and Bryant Road Pipelines & Pump Station Environmental Permits Consideration of Invasive Species (Mussels)	Project Team Community Television Broadcast on the LOIS Project Fact Sheet [PDF 220 kb]

Questions not answered here? Contact the Lake Oswego Interceptor Office: (503) 699-7466.

If your community or neighborhood organization would like a presentation on the status of this project, please contact the City's project manager at the number provided above.