Many Hillsboro-area residents and businesses could be getting much of their water from the Willamette River in 10 years or so.

That’s what the Hillsboro Utility Commission currently thinks is the best way to prevent a water shortage predicted to hit around 2022. The three-member commission is responsible for overseeing the city’s water TRIBUNE PHOTO: CHASE ALLGOOD - The cost of increasing the capacity of Hagg Lake is prohibitive, officials now say.

After studying a variety of options, including raising the Scoggins Dam in Hagg Lake and buying water from Portland, the commission is leaning toward drawing water from the Willamette River near Wilsonville to help meet the city’s future needs.

An analysis by the Hillsboro Water Department concludes that is the most affordable option, even though it requires building a water treatment plant in Wilsonville and a 20-mile pipeline to the city.

“The Willamette River in Wilsonville is the best new source of water,” says Kevin Hanway, the department’s executive director.

With approval by the commission, the department has scheduled a series of forums to discuss the option with Hillsboro residents and businesses. Two public workshops are scheduled. The first will be held from 6 to 7:30 p.m. on Oct. 25 in Room 113B at the Hillsboro Civic Center, 150 E. Main St. The second will be held from 6 to 7:30 p.m. on Nov. 14 in the Main Library, 2850 N.E. Brookwood St.

The commission is scheduled to select the preferred long-term water supply option in February. Even though the commission is leaning towards the Willamette River in Wilsonville, a number of things will have to happen for it to be guaranteed. They include partnering with the city of Beaverton and the Tualatin Valley Water District for the construction of the treatment plant and pipeline. Both Beaverton and TVWD are studying their own long-term water needs and have not yet selected their best options.

Even if Beaverton and TVWD partner on the Wilsonville plant, the cost to Hillsboro is currently estimated at $370 million. Water rates would likely to be raised a yet-to-be determined amount to finance revenue bonds to pay the city’s share.

Hefty costs

Hillsboro provides water throughout much of Washington County. In addition to meeting the needs of the city, Hillsboro-owned facilities provide water to Forest Grove, Cornelius, Gaston, the LA Water Co-op and much of the area served by the TVWD.

During the rainy months, Hillsboro is able to meet most of these needs from the Tualatin River. But it relies on the water behind Scoggins Dam and the in the Barney Reservoir in the summer when the river runs low.

Hillsboro officials have known for many years that population and business growth will someday outstrip existing water resources. For most of that time, it was assumed the best solution was raising the Scoggins Dam about 40 feet. Preliminary estimates pegged the cost between $10 million and $15 million, a relatively inexpensive solution.

But a study of the dam conducted in 2008 raised serious questions about that idea. It found the dam sits on a seismic fault and would likely fail during the kind of serious earthquake predicted to eventually occur here. The cost of both reinforcing and raising the dam suddenly increased to around $1 billion.

Hillsboro officials are still pressing the U.S. Bureau of Reclamation, which owns Scoggins Dam, to reinforce it. The bureau is scheduled to release the results of a three-year study of options on Oct. 11. But the idea of also raising the dam — called the Tualatin Basin Water Supply Project — has been placed on hold.

After the results of the study were known, the commission directed the department to review all available options for additional water. The Willamette River in Wilsonville was a logical choice. A treatment plant built there has been providing the city of Wilsonville with all of its water for 10 years without any problems. The city of Sherwood recently began buying water from it, too.

The plant is partly owned by the TVWD and was built with an intake pipe large enough to meet Hillsboro’s future needs.

The Wilsonville site is called the Mid-Willamette Option. By way of comparison, the department also looked at building a treatment plant near Newberg and a pipeline to the city. It is called the South Willamette Option.

The department also looked at buying water from the city of Portland, which already has a number of other wholesale customers. It is called the Portland Supply Option.

Although the water from the Bull Run Reservoir is clean, it is unfiltered and varies too much in quality for many of Hillsboro’s industrial customers. As a result, the department concluded it would need to build a plant to treat Portland’s water on its way to the city.

Finally, the department looked at building wells and a pipeline to tap groundwater supplies near Scappoose. Called the Northern Groundwater Option, it was complicated by a lack of research into the quality of the water there.

Preliminary cost estimates showed the Mid-Valley Option was the least expensive. It came in at $870 million, with Hillsboro’s share pegged at $370 million.

The Southern Willamette Option was $995 million without any partnership opportunities to reduce Hillsboro’s cost.

The Portland Supply Option was $1.1 billion, with Hillsboro’s share being $725,000 if Beaverton and the TVWD participate.

The Northern Groundwater Option was $1.14 billion, with Hillsboro’s share estimated at $450 million, depending on partnership opportunities.

Mid-Willamette option

At its Sept. 18 meeting, the commission agreed with the staff report and designated the Mid-Valley Option as the Preliminary Preferred Option. The commission also directed the department to launch an outreach campaign to inform the public about the city’s future water needs and idea of building a treatment plan tin Wilsonville to meet them.

“The mid-Willamette option provides for high quality tap water at a lower cost, with less implementation risk, than the other viable alternatives,” commission Chairman John Godsey said in a prepared statement announcing the decision.

Existing customers west of Hillsboro will not receive water from the new source.

Detailed information is available on the city website devoted to the project,

Tracy Steele, the department’s public information officer, says it will soon include the complete schedule of outreach forums and the detailed analysis of each option.

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