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Portland Water Bureau

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Washington Park Reservoir Improvements Project: April 2016 Update


In order to comply with federal and state mandates and ensure a healthy, resilient, and secure water system, the Portland Water Bureau and Oregon general contractor Hoffman Construction Company are moving forward with an eight-year capital improvement project to update the Washington Park reservoir site at 2403 SW Jefferson Street.

Currently, Washington Park’s open Reservoirs 3 (upper) and 4 (lower) occupy the site along with two gate houses, a weir building, three pump houses, a generator house, and associated underground piping. The reservoirs are part of an ingenious gravity‐fed drinking water system constructed more than 120 years ago in 1893 and 1894, respectively.



The project entails building a new, seismically reinforced below ground reservoir. The reservoir will not only maintain the historic drinking water function provided by the original reservoirs, but will be engineered to withstand ongoing landslide encroachment and potentially catastrophic effects of a major earthquake and will feature a reflecting pool on top in the same general footprint as the historical Reservoir 3.


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

When complete and online, the new underground reservoir will supply water to Portland’s west side, including all downtown businesses and residents, the Oregon Zoo, more than 60 parks, six hospitals, and 20 Portland public schools.

Four major challenges are driving this project: aging facilities, seismic vulnerability, an ancient landslide, and the Long-Term Enhanced Surface Water Treatment Rule (LT2).

  1. Aging Facilities: Reservoirs are typically designed for 100 years of service. The two Washington Park reservoirs are more than 120 years old. Condition assessments performed at the Washington Park Reservoir site in 1997 and 2001 confirmed the reservoirs and structures were nearing the end of their useful service life.
  2. Seismic Vulnerability: The original facilities were designed and constructed prior to current seismic standards. They do not meet structural requirements for current anticipated seismic activity and, therefore, are vulnerable to severe damage or failure during a significant seismic event. Failure of these reservoirs and structures could be catastrophic, resulting in the loss of drinking water to the west side of Portland.
  3. Landslide: Washington Park’s ancient landslide at the reservoir site has been continuously damaging both reservoirs since original construction in the late 1800’s.
  4. Long-Term Enhanced Surface Water Treatment Rule (LT2): The 2006 federal regulation requires the City of Portland to protect its stored drinking water against contamination as part of the water quality requirements for safe drinking water. To address this requirement, the City is constructing alternative buried storage, allowing the uncovered reservoirs to be taken off‐line.

The project is part of the Water Bureau’s Capital Improvement Program and funded by revenue bond proceeds paid back with utility ratepayers’ fund. 

The project is happening now in order to meet four key deadlines identified in the compliance schedule approved by the federal Environmental Protection Agency and enforced by the Oregon Health Authority: 

  • March 30, 2016: Complete design
  • July 1, 2016: Begin construction
  • December 31, 2019: Complete Reservoir 3 construction
  • December 31, 2020: Disconnect Reservoir 4 from the city’s water system


Tree Pruning / Inspection Within project site, around the reservoirs, along SW Sacajawea Blvd, SW Lewis Clark Way, & SW Madison Ct          
Miscellaneous Site Work Inside Portland Water Bureau fencing          
Construction Fence Installation Project site          
Placement of Mobile Field Offices Project site, below Reservoir 4          
Vegetation / Tree Removal Around the reservoirs, by SW Sacajawea and Sherwood Blvds           
Erosion Control Project site          
Remove Steel Grillage, Fencing Project site          
Remove Weir Building East of Reservoir 3          

The project will span eight years; the first two years will trigger the most significant impacts to traffic, transportation, and parking in the park.

Park users are encouraged to travel to and move safely around the park and its attractions by using the bus and light rail, walking, biking and skating, and taking the free park shuttle. Visit and  for transit options.

Following is a description of upcoming project work and impacts spanning now until August 2016.

April – May 2016
Vegetation and trees will be removed below Reservoir 4 near the pump station facilities and adjacent to SW Jefferson Street. All work will occur within the project site. Selective tree pruning and inspection will also occur within the project site, around the reservoirs, and along SW Sacajawea Boulevard, SW Lewis Clark Way, and SW Madison Court.

  • Traffic Slowing: Travelers are encouraged to exercise caution and drive slowly around tree pruning work areas on SW Sacajawea Boulevard, SW Lewis Clark Way, and SW Madison Court. Pruning will occur intermittently Monday through Friday, between 7 a.m. to 4 p.m.

May - August 2016
Early site preparation work will occur, including construction fence installation, placement of mobile field offices, tree/vegetation clearing, and erosion control. 

  • Traffic Delays: Travelers may experience intermittent traffic flow delays up to 20 minutes on SW Sacajawea and SW Sherwood Boulevards due to pre-construction maintenance and removal of vegetation and trees in and around the project site.
  • Parking: All parking will remain open on SW Lewis Clark Way and SW Sacajawea and SW Sherwood Boulevards.
  • Park Facilities: All park facilities will remain open.
  • TriMet Bus Service: TriMet Bus Line 63 may have minor delays. Stop ID 6177 at SW Sacajawea/ Sherwood may be intermittently affected depending on pre-construction activity. Check for real time updates.

To contact us with questions or concerns or to change your preferences on how to receive project updates:


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