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Portland Water Bureau

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Kelly Butte Reservoir Construction Complete, Scheduled to Go Online Spring 2015

January 2015 aerial photo of Kelly Butte Reservoir worksite
Early January 2015 aerial photo of Kelly Butte Reservoir worksite

On schedule and in just over two years, the Portland Water Bureau and Hoffman Construction Company crews have completed construction of the 25-million gallon underground reservoir, overflow basin, and an intricate network of underground piping, multiple vaults, and valve structures at Kelly Butte in southeast Portland.

The underground reservoir’s 394-foot by 296-foot floor, walls, 252 supporting columns, and roof were strategically poured during 2013 and 2014.

Functional testing of the new reservoir and valves will be complete within the next few months.

Backfill around reservoir
Crews backfilling around the reservoir

Crews are now working to backfill around and on top of the underground reservoir with onsite earthwork. During February and March, the reservoir and piping are scheduled to undergo disinfection.

Improving the Landscape

A year ago, crews removed non-native and invasive plants, dead and diseased trees, and unfortunately a few healthy trees to accommodate the footprint for the new underground reservoir. On the east and north side of the butte, the tree canopy that is dominated by Douglas-Fir and Big Leaf Maple trees was largely left intact. 

Within the next couple months, the Water Bureau and Hoffman Construction crews will undertake a comprehensive re-vegetation management project on the butte.

Re-vegetation plan at Kelly Butte
Re-vegetation plan at Kelly Butte

An important part of the approved land use review application, the project includes the strategic planting of more than 1,660 trees and 7,250 shrubs across the entire site.

Planting areas will be maintained so that the newly planted trees and clusters of shrubs are free to grow.

To help prevent and mitigate soil erosion, especially on the hillside slope, crews seeded ground cover plants which have already begun sprouting across the butte.

What’s Next

  • Conduct site landscaping and restoration efforts, including mitigation plantings.
  • Install permanent gates and fencing around the reservoir.
  • Develop maintenance roads, providing access to the reservoir and supporting structures.

The entire project is slated for completion by the end of 2015.

The Kelly Butte Reservoir will serve Portland's east side and be a stopover to supply water to the Washington Park reservoir and southwest Portland area water storage tanks.

For additional information on the Kelly Butte Reservoir project, visit

Lindsay Wochnick
Public Information


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