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The City of Portland, Oregon

Portland Water Bureau

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Washington Park Reservoir Improvement Project

  • Project Updates Stay in the know about project progress! Sign up to receive emailed updates.

  • Upper Reservoir - Pump House View The new reservoir is engineered to withstand ongoing landslide encroachment and seismic events.

  • Serving Portland Since 1895 When completed, the new reservoir will provide service for at least another 100 years.

  • Lower Reservoir 4 - Downtown View A lowland wildlife habitat area, bio-swale, and reflecting pool will be constructed.

  • Supplying Water to Portland's West Side Serving more than 360,000 people, 20 schools, three hospital complexes, 60 parks, and major attractions.

  • Upper Reservoir 3 - Grand Staircase View The new reservoir, in the footprint of the historic Reservoir 3 (upper), features a reflecting pool at ground level.

  • Washington Park Reservoir Improvement Project A new 12.4-million gallon, seismically reinforced underground reservoir.

  • Lower Reservoir 4 - Powerhouse View Existing Reservoir 4 (lower) will be disconnected from the public drinking water system.

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Updated: July 23, 2020

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What's happening now 

During COVID-19, the Water Bureau continues to work on critical infrastructure projects like Washington Park Reservoir. Projects like this contribute to the economy and support our workforce. We are closely following OSHA, the governor’s and the CDC’s safety guidelines to keep our crews and their families safe.

Roof pours

This summer, we are pouring sections of the reservoir roof. Managing the placement and curing of concrete at the Washington Park Reservoir Improvement Project is a delicate act, particularly during the warmer months. As concrete is placed and begins to cure, its temperature heats up. During warm weather, it can heat to temperatures that cause damage to the finished concrete. Also, to make sure that the concrete we pour stays consistent, we arrange for upwards of 40 truck loads to be poured and pumped one right after another. We start early in the day in order to control the heat levels so that the finished concrete is strong, and to make sure that we can finish our pour in one long day.

The good news is that once this work is complete, we will be able to remove the cranes, and the rest of the early morning work will take place inside of the reservoir where sounds will be more muffled.

Here's what to expect with roof pours:

  • Pours per week: Twice-weekly pours, Wednesday and Thursday through the end of August, with pours taking place through October
  • Sequence/Location: Starting the week of July 27th, crews will begin pouring concrete at the northern end of the reservoir.
  • Start time: 2:30 a.m. on warmer summer days, later on cooler days
  • Number of pours to complete the roof: 21
  • Number of trucks for each pour: 35 (48-50 for three of the remaining larger pours)
  • Truck Routes: Trucks arrive via SW Park or SW Jefferson (same as before)

Stabilizing an ancient landslide

In the area that was formerly Reservoir 4, crews are continuing work on a reinforced soil slope. They are layering rock, geotextile (plastic fabric), and engineered fill (a specialized mix of soils) to build up the hill. This will also provide drainage to prevent water from destabilizing the new slope and existing landslide. The combination of different materials allows crews to build a steeper hillside that will look similar to what was here before construction of the original reservoir in 1894. 

Trail and other closures

Madison Trail: Our contractor is accelerating their process to finish their work by this fall. That means they are carrying a higher volume of materials overhead an sending more traffic along Madison Trail. The trail will remain closed to keep people safe and to reduce the inconvenience of intermittent openings and re-closures. We expect this work to be complete and the trail to re-open by early fall. We apologize for the inconvenience. We're hoping our neighbors will put up with the temporary inconvenience knowing that it allows us to complete some of our more impactful work like concrete pours and crane lifts sooner than anticipated.

Other park closures: Explore Washington Park added a COVID-19 resource page to their website with updated maps and information about openings, closures and safety suggestions at

See photos of work performed over the past month in our most recent e-newsletter HERE.

Concrete Pour Dates

Dates are approximate and may change due to weather, material availability, or other factors. Work can begin as early as 2:30 a.m. on these dates. Due to the size and volume of concrete needed, deliveries will begin in the early morning, with new concrete trucks arriving approximately every 3 - 5 minutes. Concrete deliveries should be completed before 6 p.m. but on site work will continue beyond that time to complete the finishing work.

Roof pours: Wednesdays and Thursdays each week through the fall

Noise Permit extension: Information HERE

To see a map of the construction site, click HERE.

Watch a video showing how the elements of the new reservoir fit together within the footprint of the historic reservoir HERE.

Project Overview

Including the project description, map and schedule

Community Outreach History

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Traffic Impacts

Beginning April 2, 2018

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