Washington Park Reservoirs Improvements Project
The Portland Water Bureau supplies drinking water to more than 950,000 people and strives to provide the highest quality water to enhance the public health and safety, and contribute to the economic viability and livability of the Portland metropolitan region. The goal of the Washington Park Reservoir Improvements Project is to provide increased reliability of stored drinking water at the City’s Washington Park Reservoirs and to protect the water supply.

Project Background
The Washington Park Reservoir Improvements Project proposes to build a new below-ground reservoir in the same general footprint as the existing upper Reservoir 3, with a reflecting pool on top. This reservoir is being built east of the landslide.

The lower Reservoir 4 basin and the slope to the west are needed to provide landslide abatement; the slope will be restored to its pre-reservoir condition. Reservoir 4 will be disconnected from the public drinking water system and a lowland habitat area/bioswale and a reflecting pool are also proposed in the Reservoir 4 basin. Work will primarily be within the Historic District.

The public will have more access to the area and aesthetic design amenities will improve the visitor experience and understanding of the site. These changes will help to:
- Meet modern public health and safety practices and standards.
- Meet federal and state drinking water mandates.
- Make the water system more reliable, resilient and secure.
- Create new facilities that can serve Portland for more than 100 years.

This project is unique because it is in a Historic District.

Project Need

The project is needed for four (4) main reasons:

Aging Facilities
Open reservoirs were typically designed for 100 years of service. The Washington Park reservoirs are now 120 years old. Currently a synthetic rubber liner is used to keep water in Reservoir 3 due to concrete cracking in the structure.

Seismic Vulnerability
Open reservoirs were not designed to withstand earthquakes; the concrete is less than 12-inches thick and has little steel reinforcement. They would likely fail during a moderate earthquake. New buried reservoirs are designed using current earthquake engineering standards with substantial amounts of rebar and stronger concrete.

Washington Park’s ancient landslide has been continuously damaging both reservoirs since they were originally constructed in 1893-94.

Long-Term Enhanced Surface Water Treatment Rule (LT2)
The 2006 federal regulation that requires the City of Portland to protect its stored drinking water against contamination.
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