Lake Oswego Water Treatment Plant

Facility Description

The City of Lake Oswego has operated a drinking water treatment plant in West Linn’s Robinwood neighborhood since 1968. The Lake Oswego Tigard Water Partnership plans to upgrade and expand the treatment plant, located between Kenthorpe Way and Mapleton Drive, to meet current and future drinking water needs. The upgraded plant will supply Lake Oswego and Tigard, and will continue to serve as West Linn’s sole source of emergency and backup water supply.

History of the Water Treatment Plant

Built in 1968, Lake Oswego’s water treatment plant was originally located in unincorporated Clackamas County. The area was later annexed by West Linn. Through its 44-year history the plant has earned a reputation as a good neighbor. The City of West Linn has approved land use applications for upgrades and expansions three times since the plant was built.

It is not uncommon for wastewater and water treatment plants to be located in residential areas. South Fork Water Board’s treatment plant – jointly owned by West Linn and Oregon City – is located in Oregon City’s Park Place neighborhood. Extensive upgrading, expansion and treatment modifications have occurred there over the past several years to serve the two communities.

Water Treatment Plant – Good Neighbor Plan

Lake Oswego Tigard Water Partnership began discussions with the Robinwood Neighborhood Association in early 2010, sharing details of the water treatment plant expansion, listening to suggestions, and finding ways for the upgraded water plant to continue to be a good neighbor. Two years later, the Partnership has met with Robinwood neighbors more than 20 times, developing a Good Neighbor Plan (pdf, 308 kb) that contains the Partnership’s commitments for design–construction–operations of the new facility. Neighborhood input played a big role in design concepts with the addition of numerous plant layout changes and amenities requested by neighbors.


How to Get Involved

  • Click here for upcoming meeting dates.
  • Sign up to receive email notices.  Mark the ‘Water Treatment Plant' as your interest.
  • Click here to contact us by email.
  • Call the Water Hotline (503) 697-6502.

Additional Information

You can find regular updates on the Work Underway page.

Field Updates

Friday - September 26, 2014

Water Treatment Plant Construction Update

Pipe installation near the center of the site (foreground) & walls being formed for the finished water pump station (background).

Ballasted flocculation – center of site

Large mechanical equipment deliveries are continuing to arrive and be installed for the ballasted flocculation. Over the next two weeks, water testing of two tanks in the south of the structure will begin.

Temporary storage building – southeast of site

Work continues on installing a temporary storage building on the southeast corner of the site (photo shown on the left). It will store large equipment arriving on site, to be installed later. The building will be removed near the end of the project.

Chemical & electrical buildings – center of site

Crews are forming and pouring the truck loading slabs for the chemical building. Starting next week, concrete blocks for the walls will be placed. Over the next two weeks, structural steel will be placed for the electrical building.

Finished Water Pump Station and Clearwell – south and center of site

Wall pours are now complete for the finished water pump station. Crews are installing piping support and next week, the exterior coating will be applied. Once this is complete, the area will be backfilled. During backfilling, neighbors close to the center of the site may experience an increase in vibration, as the compactor compresses fill. Over the next few weeks, crews will begin cleaning the clearwell tank and filling it for the water test.

Miscellaneous piping

Installation of the 30” – 48” piping across the site continues, including excavating, placing the pipe, encasing it in concrete and backfilling the trench. During the excavating and backfilling, neighbors may experience an increase in truck traffic, noise and vibration.

Work hours

Work hours are Monday to Friday from 7:00 a.m. to 7:00 p.m. and Saturdays, from 9:00 a.m. to 5:00 p.m. Please refer to the current site plan for locations of each structure.

WTP construction tours – next tour is October 16

Due to scheduling and holiday conflicts, October and December tours will be held on the third Thursday of the month at 10 a.m. (October 16 and December 18). Advance registration is required and space is limited. Please contact us to sign up for a tour!

Neighborhood construction meetings – first and third Tuesday of the month

The next meeting will be held on October 7, at 7:30 a.m. in the downstairs restaurant area at Burgerville, 18350 Willamette Drive, West Linn. Please come along to stay updated on construction progress in West Linn and ask questions of the project team. All meeting materials are posted online under “past meetings and events.”

For more information, please email lotwater@ci.oswego.or.us, call the hotline at 503-697-6502.

Thursday - September 18, 2014

How is the new water pipeline being built under the Willamette River?

A drill rig loading drill pipe for the pilot hole, at the construction site just north of Mary S. Young Park, West Linn

Over 10 miles of large diameter water pipeline is currently under construction in Gladstone, West Linn, Lake Oswego and Tigard as part of the Lake Oswego-Tigard Water Partnership project. Construction methods for the pipeline vary between traditional cut-and-cover trenching and trenchless methods including horizontal directional drilling, micro tunneling and pipe ramming. While much of the pipeline is being installed in streets using typical cut-and-cover trenching, a special technique is used to get across the Willamette River.

Read More

Thursday - September 18, 2014

West Linn Pipeline Construction Update

Crews are making the final pass under the river, using a drill bit or reamer to enlarge the hole for the pipe to be pulled through in October.

Drill pipe is attached to the reamer.

Construction updates include all current or upcoming pipeline work for the project in West Linn. Read below for specific information on the following:

  • Horizontal directional drilling under the river, near Mary S. Young Park
  • Highway 43 pipeline construction (night work) - expected to start this fall
  • Neighborhood construction update meetings - first and third Tuesdays of the month

Read More