Preferred Option


Evaluation Results Map

The Utilities Commission measured each potential source option against the set of 10 criteria that was selected by them after receiving input from their staff and customers. The Mid-Willamette option was the least expensive option, had the most positives and was the only option that successfully met all of the criteria. Here are detailed explanations why the mid-Willamette scored so highly and came out on top as the preliminary preferred option.

  • Treated Water Quality: The highest priority for the Utilities Commission is to protect customer health by consistent delivery of high-quality drinking water. Water drawn from the Willamette River would be treated to the highest standard available and would consistently meet or surpass all Safe Drinking Water Act standards. The high quality of the treated drinking water from the Mid-Willamette source has been confirmed by the experience of two communities that already receive their drinking water supplies from this source. Wilsonville has been getting all of its drinking water from the Mid-Willamette source for 10 years, and Sherwood recently converted its water system to be dependent on this source. Wilsonville has met all drinking water standards over the last 10 years.
  • Reliability: The Mid-Willamette option has a positive rating compared to most of the other options. It is less susceptible to impacts from drought or climate change because of the large size of the watershed above the diversion point, and the large number of storage impoundments upstream of this source. The reliability of this option is also increased in comparison to some of the other options because the new treatment plant and transmission facilities would be built to current seismic standards.
  • Redundancy: The Mid-Willamette option provides an additional source of water supply for Hillsboro. It shares this benefit with all of the options other than the Hagg Lake expansion option. Currently, Hillsboro is entirely reliant on its single source of supply through the Joint Water Commission and the Tualatin River basin.
  • Ownership: Hillsboro's history of successfully planning for the challenges of meeting its water supply needs have depended on its ownership interests in all the elements of the water supply system, beginning with its water rights and stored water facilities, and continuing through ownership of the treatment and transmission facilities. It was also clear from input received from Hillsboro's water customers that they place a high value on the ability of the city to own and control its water rights and infrastructure. The Mid-Willamette option provides the Commission with the same opportunity for asset ownership that has been effective for the city through the Joint Water Commission.
  • Operational Complexity: Hillsboro currently operates the largest conventional water treatment plant in Oregon, and a water transmission system that serves over 400,000 residents across Washington County. The treatment and transmission systems for the Mid-Willamette option would be similar in configuration and sophistication to the system already operated by the city.
  • Implementation Risk: The Mid-Willamette option rated higher than all of the other options on this criterion. The level of risk involved is important because of the high capital investment that is required and the lengthy timeline for acquiring right-or-way, designing improvements, obtaining environmental approvals, and then constructing the necessary improvements. To assure that the Commission can successfully deliver those improvements on a timeline that meets the needs of the next generation of customers, it needs to minimize the potential later in the implementation process that the necessary approvals could not be obtained, or that the costs associated with conditions imposed on those approvals would make the project unfeasible. Those risks were rated lowest for the Mid-Willamette option because:
    (1) water rights are available to the city through new permits or through agreements to obtain interests in existing water right permits; and
    (2) since the risks associated with obtaining approvals to build a new raw water intake are high, the Mid-Willamette option rates higher because an intake is already in place and there is no need to build a new intake.
  • Source Water Quality: The Mid-Willamette option was rated neutral for this criterion. These facilities would be taking water from the Willamette River well upstream of the Portland metropolitan urban area and the Portland Harbor superfund site. Upstream of the Mid-Willamette facilities is a relatively large watershed, which increases the risk of potential contamination from urban and rural influences. However, this option benefits from the extensive water quality database and monitoring system that is available for the Willamette River. Hillsboro is committed to source water protection programs and emergency response planning for any water source option. These programs allow for potential risks to be addressed through design of treatment systems and operations and through proactive watershed management.
  • Environmental Impacts: All of the options involve some environmental impacts. The impacts associated with the Mid-Willamette option are neutral compared to the other options. Most of its impacts would occur during construction and could be mitigated; since there is no need to build a new raw water intake, the impacts of in-river construction work are minimized. Impacts from power usage during plant operations are moderate compared to some other options.
  • Responsiveness to Demand Growth: Water treatment plant capacity for the Mid-Willamette option could be built in phases as the need for water increases. This option also holds the potential for additional long-term expansion beyond the planning period that was addressed by the water supply study.