A History of Lake Oswego and Tigard's Water Systems



Lake Oswego incorporates as a City.


The City of Oswego purchases a water system from Oswego Light and Power in 1925. The system consists of 7 miles of pipe, one reservoir (10th Street) and one pump station. The water sources for the system are groundwater wells and a connection to Portland’s Bull Run source.


Tigard incorporates as a City.


Wells supply water to the Tigard area.


Poor well water quality and the desire to own a more reliable source of water leads Lake Oswego to consider other source options. The Oswego City Council initiates a study of new water source options. They consider Bull Run, and the Tualatin, Willamette, and Clackamas Rivers as potential sources. Oswego Council selects the Clackamas over Bull Run in spite of its higher cost of development. Ownership and control of the system outweigh cost considerations.


Oswego acquires water rights on the Clackamas River for its drinking water supply.


Tigard Water District issues summer peak curtailments due to well capacity limitations to meet growing system demands and dropping water tables. In 1972, the state engineer declares the Cooper-Bull Mountain region a critical groundwater area, greatly reducing Tigard's access to further or even future groundwater rights.


Lake Oswego enters into a surplus water sales agreement with the Tigard Water District. 


Portland and Lake Oswego pipes are installed for wholesale water supply to Tigard. 


The Tigard Water District considers connecting to the Willamette River near Newberg with a “Ranney” collector well, but pulls the ballot initiative due to conflicts in engineering cost estimates.  


The City of Tigard develops future water supply plans to tap the Willamette River at Wilsonville, but is turned back by a voter initiative in 1998. 


City of Tigard joins the Joint Water Commission as a junior partner to participate in the Hagg Lake Dam Project.


The Hagg Lake Dam Project bogs down in federal ownership and seismic safety concerns.


In September 2005, the cities of Tigard and Lake Oswego complete the Water Supply Feasibility Project study. In March 2006, the two cities fund the Joint Water Supply System Analysis. This analysis investigates the technical, financial and legal issues around a potential partnership. Ultimately, the planning concludes that each city would benefit from jointly expanding the Lake Oswego water system.


Representatives from each of the two cities form a work group to further explore the water partnership. The City of Tigard withdraws from the Joint Water Commission. The Cities of Tigard and Lake Oswego and the Intergovernmental Water Board enter into a Memorandum of Understanding (MOU) developed by the work group in December.


At a signing ceremony on August 6, 2008, Tigard Mayor Craig Dirksen and Lake Oswego Mayor Judie Hammerstad officially sign a water partnership agreement between the two cities.


Planning, permitting and design takes place for the six major facilities of the new water system. From 2010 – 2011 a Citizen Sounding Board and Technical Committee is formed to assess and determine the new water treatment method to be used as part of the partnership project.


Construction starts on a new river intake pump station in Gladstone (May), the water treatment plant in West Linn (August), and the first segment of 10½ miles of large diameter water pipes in Lake Oswego (November).


Construction starts on the Waluga Reservoir 2 in May. In June, a groundbreaking is held with Tigard Mayor John Cook and Lake Oswego Mayor Kent Studebaker, to celebrate the start of construction at the Bonita Pump Station in Tigard. In the summer, raw water pipe construction begins in Gladstone. Horizontal directional drilling begins for installation of 3,900 ft. of pipe under the Willamette River, at Mary S. Young Park in West Linn and Meldrum Bar Park in Gladstone.

On October 30, 3,900 ft. of pipe is pulled through the pre-drilled hole under the Willamette River in less than 12-hours.

In late fall, nighttime construction commences on a 2-mile stretch of Highway 43 in Lake Oswego and West Linn for a segment of the finished water pipeline.


In March, construction of the river intake is completed and the pump station begins pumping water to the treatment plant in West Linn. Pipeline construction begins in Tigard on Bonita Road.

In May, pipeline construction begins on Mapleton Drive in West Linn.

Over the Fourth of July long weekend, emergency water is supplied to West Linn due to a main break.

In summer, the Partnership hosts a dedication ceremony for a new cultural resources exhibit installed as part of mitigation for pipeline construction. The old river intake pump station is demolished and construction is completed on the new Waluga Reservoir 2.

In fall, two ribbon-cutting events are held with elected officials, city staff and neighbors for the river intake and new reservoir. Construction is completed on the Bonita Pump Station and Tigard begins testing the station, in preparation for the new supply connection. The new 2 ½ mile raw (untreated) water pipe is placed into service, pumping water from the river to the water treatment plant in West Linn.


In early spring, construction is completed on more than 10 1/2 miles of seismically resilient, large diameter water pipelines – the backbone of the new system. The new eight-mile-long treated water pipeline is placed in service, delivering clean drinking water from the treatment facility in West Linn to the Waluga Reservoir site in Lake Oswego and onto Tigard’s new Bonita Pump Station. Tigard continues preparations for the change in water supply from unfiltered Bull Run water, to filtered Clackamas River water.

In late spring, the second of three major phases of construction is completed at the water treatment plant and six new filters are placed into service, with a capacity of 32 million gallons a day.

On June 9, the water treatment plant begins supplying water to Lake Oswego and Tigard customers, known as Tigard’s Water Independence Day.

In summer, the final stage of demolition is completed at the water treatment plant, and all 1,150 concrete piles (56,000 linear feet) are installed for seismic resiliency at the facility.

In fall, construction starts on the replacement of the Waluga Reservoir 1’s roof and columns. The Partnership receives a $265k award and reimbursement from the Energy Trust of Oregon for implementing energy savings at the water treatment plant. The contractor completes the placement of more than 18,950 cubic yards of structural concrete for the plant’s new structures (equivalent to 1,900 truckloads).


In spring, the third and final major phase of construction is completed at the water treatment plant, with a new, state-of-the-art ozone system placed into service. Construction of the Waluga Reservoir 1’s new roof and columns is completed at the Waluga Reservoir site in Lake Oswego.

Over the Fourth of July long weekend, 6 MGD of water is supplied to the City of West Linn via the emergency intertie, during a major City of West Linn main break on the Abernethy Bridge.

In late summer, all site work and landscaping is completed at the plant. A new pedestrian pathway linking Kenthorpe Way and Mapleton Drive is opened at the plant site, along with 2-acres of park-like amenities. A ribbon-cutting is held to commemorate the new pathway and public areas with water treatment plant neighbors.

In early fall, a project completion celebration is held with elected officials, dignitaries, staff, consultants and key personnel that have worked on the project.