Project Information

Introducing the Partnership

In August 2008, the cities of Lake Oswego and Tigard formally endorsed a partnership agreement for sharing drinking water resources and costs.  Lake Oswego’s water supply system is near capacity, and key facilities need expansion and upgrades.  Tigard residents need a secure, dependable water source.  Both cities want to keep water affordable for their customers and sharing the cost of new infrastructure to serve both communities does that. 

Conserving water is the first and most important supply option for the Lake Oswego Tigard partnership.  Effective conservation measures alone, however, won’t be enough to meet the two cities’ needs.

This regional collaboration isn’t new.  Lake Oswego and Tigard have benefitted from a water supply relationship dating back to the 1970s – Lake Oswego as the seller of water, Tigard as the buyer. The Oregon Department of Water Resources and the conservation community encourage regional water supply planning and collaboration between multiple communities as a smart way to manage water needs.

Water System Improvements and Construction Schedule

This map shows planned facilities improvements and the current construction schedule.  Click on the map for a larger version.

Recommended Facilities Map

The partnership will upgrade, upsize and expand Lake Oswego’s existing drinking water facilities – at or near their current locations – to serve the needs of Lake Oswego and Tigard customers.

  Click to download a larger pdf version of the recommended facilities map. (pdf, 285 kb)

Water System Improvements

The Lake Oswego Tigard Water Partnership expands Lake Oswego’s existing drinking water infrastructure so that it can serve both communities.  Lake Oswego currently withdraws water from the Clackamas River in Gladstone as it has been for over 40 years.  This water travels through a large pipe under the Willamette River to a facility in West Linn where it is finished to safe drinking water standards.  The finished water is then pumped through another large pipeline to Lake Oswego and the Waluga Reservoir near the City’s western boundary.  From there, water goes through pipes to Lake Oswego customers and to Tigard’s Bonita Road pump station. 

The Partnership project will upgrade, upsize and expand six existing facilities:

  1. The Clackamas River intake in Gladstone
  2. The pipeline that conveys raw water to the water treatment facility
  3. The water treatment facility in West Linn
  4. The pipes that convey finished water to Lake Oswego and Tigard
  5. The Waluga Reservoir in Lake Oswego that provides water storage for Lake Oswego and needed capacity to provide water to both communities
  6. The Bonita Road pumping station in Tigard.

Click here to visit our water facilities page.

To learn even more about the project, read Water Savvy, the project's technical newsletter.  You can find copies for download in the project library.

Project Schedule

The project started in December 2009 and continues through 2016.  Work occurs in four overlapping phases. As these phases progress, a detailed schedule will be made available.

During Project Definition, a drinking water treatement recommendation was made by a panel of experts brought in to consult on the project.  Click here to learn more.

Phase Anticipated Duration
Project Definition December 2009 - December 2010
Pre-Design and Permitting July 2010 - February 2012
Design March 2011 - July 2013
Construction 2013 - 2016

Construction Impacts

Most pipeline for the project is installed in the public right of way. There are two exceptions, where the pipeline tunnels under the Willamette River and under Oswego Lake. Read the (792 kb, May 2014) for more detailed maps and information about the construction process.

Visit the In Your Area page to learn about activities planned in your neighborhood. The Work Underway page includes a list of active work and activities that are planned in the next month.


Project Benefits Both Cities

The Partnership is the culmination of Tigard’s 15-year search for a stable source of water.  Tigard customers benefit by finally obtaining a secure, dependable, affordable drinking water source.  Lake Oswego water customers benefit by sharing the costs for needed upgrades to the community’s water system.

To learn more, read Water Savvy, Issue 3: Time to Prepare for the Future, April 2010  (pdf 1 mb)


Environmental Protection

Lake Oswego and Tigard are committed to protecting and enhancing water quality and fish habitat in the Clackamas River, and are already working with Clackamas River Water Providers, Clackamas River Basin Council, US Geological Survey, PGE and Clackamas County Water Environment Services to improve watershed conditions.

Extensive federal and state environmental permit processes are in place to protect the Clackamas River and other natural resources.  The project must meet all requirements of the agencies that hold permitting/approval authority.

To learn more, read Water Savvy, Issue 7: A Close Look at Environmental Permitting, November 2010  (pdf 874 kb)

Program Costs

Project costs are allocated under an agreement between the two cities. The capital cost split is based on preliminary calculations that take into account the peak water capacity each community will receive from the upgraded system. A preliminary estimate indicates total capital costs would be allocated 47% to Lake Oswego and 53% to Tigard. This split recognizes Lake Oswego's ownership of existing facilities.

Upgrades are paid for by selling bonds backed by customer utility rates - you may have noticed changes to the water portion of your utility bill. If you are a water customer of Lake Oswego or Tigard Water, you can find helpful information about your bill at the following locations:

As designs for project facilities are completed, cost estimates change. To learn more about project costs, read Water Savvy, Issue 4 Project Costs and Savings, June 2010  (pdf 762 kb).

Focus on the Bottom Line

The Partners are working to ensure that the program delivers the most value for the dollars spent. During design, the program team will ensure that every construction project is right sized and cost-effective. The team will focus on the bottom line by:

  • Extensive ‘value planning’ to ensure that the community gets the facilities it needs at the lowest cost.
  • All contractors must be “pre-qualified” to show that they have the right type of experience, bonding, cost containment and project management experience to do the job.
  • Packaging individual construction projects. Facilities will be packaged and scheduled to take full advantage of the favorable bidding climate.
  • Pilot testing several processes (ozone, filtration and solids drying) to ensure these systems will work optimally when they are installed, saving money and guesswork in the future.
  • The project is guided by an Oversight Committee made up of two City Council members from each city to keep the project on schedule and within budget. 
  • The Oversight Committee and Councils have put guidelines in place to minimize delay—a major cause of cost increases.
  • Implementing improved business practices in the water utility to increase efficiency and maintain strong credit ratings.
  • Monitoring capital debt markets. Optimally timed debt issues will ensure the lowest rate increases over time.

How the Partnership Works

Under the partnership agreement, the City of Lake Oswego will manage and build the water system improvements.  An Oversight Committee provides leadership and guidance, with representatives from Lake Oswego and Tigard City Councils.  A Technical Team includes staff from both cities. 

Costs will be allocated to Lake Oswego and Tigard. For more information, read the Partnership Agreement between the two cities. The primary funding source is revenue bonds repaid by customers’ monthly water charges.

Public agencies typically sell bonds to fund large capital projects.  Both cities have increased water rates to pay back the principal and interest on bonds.


1909 Lake Oswego incorporates as a City.
1925 The City of Oswego purchases a water system from Oswego Light and Power in 1925. The system consists of 50,000 feet of pipe and one reservoir (10th Street). The water sources for the system are groundwater wells and a connection to Portland’s Bull Run source.
1959 Tigard incorporates as a City.
1938-1974 Wells supply water to the Tigard area.
1965 Poor well water quality and the desire to own a 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, Tualatin, Willamette, and Clackamas Rivers as sources. The 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.
1966-1969 Oswego acquires water rights on the Clackamas and designs the system still in use today.
1968-1973 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.
1974-1975 Portland and Lake Oswego pipes are installed for wholesale water supply to Tigard. 
1980 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.  
1997-1998 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. 
2001 City of Tigard joins the Joint Water Commission as a junior partner to participate in the Hagg Lake Dam Project.
2005 The Hagg Lake Dam Project bogs down in federal ownership and seismic safety concerns.
2005-2006 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 the potential partnership. Ultimately, the planning concludes that each city would benefit from jointly expanding the Lake Oswego water system.
2007 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.
2008 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.

Learn More

Click here to download the project fact sheet. (PDF 641 kb)

Click here to download frequently asked questions. (pdf 220 kb)

For more information about the Lake Oswego Tigard Water Partnership contact:

Jane Heisler
Communications Director
City of Lake Oswego, Oregon

Dennis Koellermeier
Public Works Director
City of Tigard, Oregon