Washington Park Reservoirs construction updates

Capital Improvement Project
Under Construction
Construction at the Washington Park Reservoirs started in 2016 and will continue until 2025. Read on for the most recent update.
This image shows an artist's rendering of what the reservoir site will look like after construction is finished, with reflecting pools, public walkways and lush vegetation. Text reads, "We're letting gravity do its thing. The soil needs to settle to ensure this project is successful. The next phase of work will begin late 2023. Additional text includes the project website, a description of the project, partner logos and accessibility statement.
2016 through 2025
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The Water Bureau has replaced its original 1894 reservoirs with a new 12.4-million-gallon, seismically reinforced underground reservoir. This reservoir supplies water to Portland's west side and serves more than 360,000 people, including all downtown businesses and residents, 20 schools, 5 hospital complexes, and more than 60 parks.

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In June 2021, the Water Bureau achieved a major milestone: activating the seismically-resilient 12.4-million-gallon reservoir at Washington Park. With this work completed, the reservoir was put in use for drinking water and emergency planning on June 29.

Since then, we've covered the reservoir and surrounding area with gravel and soil and will wait up to two years for gravity to do its work, settling the soil around the reservoir. We will return in 2024 to install the reflecting pool and interpretive elements, restore the historic resources, and open the area to the public for the first time in decades. Stay tuned for a grand celebration.

And, in the meantime, enjoy this 360-degree panorama view taken from atop of the Reservoir 3 dam.

Happening now

Monitoring ground movement

Map showing the northern portion of Washington Park, and the location of two work areas west of the tennis courts, and two work areas on the eastern edge of the Rose Garden along a maintenance road.
Map showing work areas in February 2022.

Starting in February 2022, the Water Bureau will replace some sensors in the park to help us measure ground movement of the slow-moving landslide between the Portland Japanese Gardens and Washington Park Reservoir. We installed some of these a few years back and are replacing them as part of ongoing maintenance. Our work will take place at a couple of locations within the reservoir construction site, on a maintenance road near the Rose Garden Amphitheater, and in the parking area next to the tennis courts. This work ensures that we can gather accurate information about soil movement near the reservoir as part of our seismic planning efforts.

What to expect:

  • When: Work is planned to start in February within the reservoir construction area. We expect to be in each location for about three to five days. Overall, the work will take about a month. 

  • What's that noise? A 140 lb. hammer is repeatedly dropped on steel rods that makes a banging noise while we sample soil. The drilling is similar to the noise from installing the drilled shafts at Washington Park Reservoir, though equipment is much smaller.  

  • What about traffic? This work will not require any road closures. The work will take place inside the construction area, on a maintenance road or in a parking stall near the tennis courts. In the area near the tennis courts, the crew will use construction cones and barricades to block off parking either the night before work or in the wee hours of the morning.  

Soil settlement 

This historic photo from the early 1900's shows two men standing on the Washington Park Reservoir Dam during construction. Text on the image reads, "We're letting gravity do its thing. The soil needs to settle to ensure this project is successful. The next phase of work will begin late 2023." Other text includes the project website, a short description of the reservoir project, and accessibility statement.

Caterpillars don't become butterflies overnight; they wrap themselves up in a cocoon, take a pause, and then unravel in breathtaking beauty. Washington Park Reservoir is entering a similar stage right now. We're covering the reservoir with gravel and soil and will wait up to two years for gravity to do its work, settling the soil around the reservoir.

During the construction pause, work will continue on the south side of the worksite to replace outdated mechanical systems inside of the hypochlorite building and upgrade pump stations and transformers. 

In addition to building new walkways and a reflecting pool, we'll plant native flowers and grasses, making a better habitat for wildlife, including butterflies. When we've completed the final stage, this park will transform into a vibrant public space we all can enjoy.

Park openings and closures

Visit the Explore Washington Park COVID-19 resource page for updated maps and information about Washington Park openings, closures, and safety.