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The City of Portland, Oregon

Portland Water Bureau

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Washington Park Reservoir Project - October 2016 Update

The Portland Water Bureau and contractor Hoffman Construction Company have started a long-term capital improvement project to update the Washington Park reservoir site at 2403 SW Jefferson Street. The project complies with federal and state mandates, seismically strengthens key water infrastructure on Portland’s west side, and helps ensure a healthy, resilient, and secure water system.

A new 12.4-million gallon, seismically reinforced below ground reservoir will be constructed in the same footprint of existing Reservoir 3 (upper) with a reflecting pool/water feature on top. The new reservoir will preserve the historic drinking water function provided by the original reservoirs and be engineered to withstand ongoing landslide encroachment and potentially catastrophic effects of a major earthquake.             

When complete and online, the new reservoir will supply water to Portland’s west side and serve more than 360,000 people, including all downtown businesses and residents, 20 schools, five hospital complexes, more than 60 parks, and the Oregon Zoo.

Existing Reservoir 4 (lower) will be disconnected from the public drinking water system and a lowland wildlife habitat area, bioswale, and reflecting pool will be constructed in the basin.

Construction started Sept. 12, 2016 and will proceed through 2020. A pause is scheduled to occur from 2020 to 2022 to allow soils to settle. From 2022 to 2024, construction of interpretive features, including the two reflecting pools and surface features, will conclude the project.


Install Tree Protection Fencing Around project site  X        
Begin Removal of Grand Staircase Within project site, by Existing Reservoir 3  X        
Remove Gatehouse 3 Platform Within project site, by Gatehouse 3  X        
Remove Plastic Liner Within Existing Reservoir 3  X        
Vegetation / Tree Removal Around the existing reservoirs, by SW Sacajawea Blvd. and SW Sherwood Blvd.  X        
Removal of Stilling Tank inside Gatehouse 4 Within project site, by Gatehouse 4  X  X      
Modify Reservoir 4 concrete liner Within Existing Reservoir 4  X  X      
Erosion Control (ongoing) Within project site, by Existing Reservoirs 3 and 4  X X  X  X 
Fill Reservoir 4 Basin Existing Reservoir 4   X  X  X  X
Construct Upper and Lower Shoring Walls Within project site, by Existing Reservoir 3   X  X  X  X
Install Piping  Under Dam 3   X   X   X

Until March 2018, major earthwork will occur along with the construction of shoring walls and the new underground reservoir. Work during this stage will cause temporary impacts to traffic, parking, and TriMet bus service.  

Current –   March 2018
Road Closures
  • SW Sacajawea Boulevard is closed to all vehicle and bike traffic and pedestrian use from the   intersection of SW Sacajawea Boulevard/SW Rose Park Road/SW Wright Road to SW Park Place.
  • SW Sherwood Boulevard is closed to all vehicle and bike traffic and pedestrian use from SW Sacajawea Boulevard to the Soccer Field.
  • SW Sherwood Boulevard is closed to all vehicle traffic from the Soccer Field to SW Kingston Avenue.
  • SW Sherwood Boulevard sidewalk is open for pedestrian use and bike traffic from SW Kingston Avenue to the Soccer Field. 
Tour Buses, Free Park Shuttle
  • Tour buses and the free park shuttle are allowed access onto SW Sherwood Boulevard at SW Kingston Drive for turnaround at the Soccer Field. No unauthorized vehicles will be permitted on SW Sherwood Blvd.
 Traffic Flow Reversal
  • The flow of traffic is reversed on SW Lewis Clark Way.
  • One-way traffic travels SW Lewis Clark Way and exits the park on SW Park Pl.
Multi-Use Shared Path
  • A designated path separate from vehicles is now available on SW Lewis Clark Way.
  • Pedestrians and cyclists can use the path to travel both in and out of the park on SW Lewis Clark Way.  
  • Cyclists are required to walk and not ride bicycles on the path.   
  • All parking spaces are closed on SW Lewis Clark Way, SW Sacajawea Blvd., and SW Sherwood Blvd. 
  • Madison Ct. Trail: Pedestrians and cyclists can enter and exit the Madison Ct. Trail on SW   Madison St. and SW Sacajawea Blvd. The trail will be closed intermittently; watch for detour signage.
  • Mac Trail: Open, not affected by project work. Continued access via SW Sherwood Blvd. and SW Sacajawea Blvd.
TriMet Bus Service
  • TriMet Bus Line 63 - Washington Park/ Arlington Heights is detoured.
  • The following stops are closed: 6177, 4346, and 4343
  • Check for updates.

The traffic control plan in place until March 2018 has been approved by the Portland Bureau of Transportation with input from Portland Parks & Recreation, Explore Washington Park, neighborhood associations, and the community. Please contact us to share any concerns related to the project, including traffic control.

General Site Work

  • Tree protection fencing has been installed to minimize impacts during construction.
  • Vegetation and trees have been removed from in and around the project site. Of the approximately 210 trees removed, 19 percent (40 trees) are non-native/invasive. Roughly 47 percent (80 trees) of the healthy, non-invasive trees removed will be used in river restoration projects in the Sandy River Basin. These projects will help create pool habitat, increase cover, and improve spawning beds for migrating, spawning, and rearing fish populations. Several trees were also delivered to the Oregon Zoo for use in primate exhibits. After construction is completed, the Water Bureau has committed to plant 20 percent more trees and shrubs than required. 

 Reservoir 3 & 4 Work

  • Existing Reservoir 4 inlet and outlet piping has been disconnected.
  • Existing Reservoir 3 Grand Staircase has been partially removed.
  • Gatehouse 3 platform has been removed.
  • The plastic liner in Existing Reservoir 3, originally installed in the 1970s and later replaced in 2003-2004, has been removed.


  • Erosion control at the site is ongoing.
  • The Stilling Tank inside Gatehouse 4 will be removed.
  • Existing Reservoir 4 concrete liner will be perforated to allow for drainage. As part of the project, existing Reservoir 4 will be removed and buried, making room for a large stormwater bioswale and wildlife habitat area with open water and connecting walkways.
  • Existing Reservoir 4 basin will be filled in order to stabilize the historic landslide. Excavated material from Reservoir 3 will be moved inside the project work site to fill Reservoir 4. This will dramatically reduce construction impacts and truck traffic to local neighborhoods.
  • Crews will begin construction on the first of two shoring walls, one temporary and one permanent, to protect the site from earth movement and allow for construction of the underground reservoir.
  • Under Dam 3, piping will be installed.

Please contact us with questions, concerns, or to sign up to receive monthly project updates.


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