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Tualatin evaluates its water source options

With a peak water demand date of 2023, Tualatin is currently looking into its water options for the coming years


As far as water goes, Tualatin is in a unique position.

With a peak demand date looming in 2023 — and not enough water currently available to the city to meet that demand — possible solutions are being evaluated and analyzed. The good news,SUBMITTED PHOTO - The line on this map represents the Tualatin Supply Line, which connects with the Washington County Supply Line at Oleson Road to bring the city water daily. Tualatin is a wholesale customer with Portland, and can currently use up to 10.8 million gallons of water a day. according to Public Works Director Jerry Postema, is that there are a lot of options.

Since last summer, a Water Supply Financial Evaluation has been underway with the city and consultant HDR to determine the varying costs between the city’s different water source options.

Currently, Tualatin gets its water from Portland as a wholesale customer, with 10.8 millions gallons available per day via the Washington County Supply Line. On peak days in the summer, Postema said the city might pump up to eight million gallons of water, but the scale is predicted to tip as early as eight years in the future. Tualatin is on a 10-year contract with Portland that it signed in 2006. Assuming neither city ends the deal, the contract will automatically renew in 2016 for another 10 years, said Postema.

“We’ve been on Portland water for an extensive period of time, and it’s a good source as everybody knows. It’s a very clean, consistent source of water,” he said. “I think the concern is more about how much water we can get from Portland, because we have restrictions.”

The options

With those restrictions, until or unless more supply line space frees up, Tualatin is maxed out at just under 11 million gallons daily. Extra water within the line is expected to be available for lease by 2026, when Tualatin Valley Water District partially switches to Willamette River water. But the city doesn’t want to bank on that as the only viable option without understanding its other possibilities.

“To get that additional water, we would probably have to get it from somewhere else,” said Postema. “Somewhere else meaning somebody may want to lease us capacity in the Washington County Supply Line, we might be able to get it from Tigard, or if the choice is to go with the Willamette, we’d go out for a vote and look at the Willamette option.”

With Tigard’s potential switch to Clackamas River water next year in a partnership with Lake Oswego, extra Portland water should be available. However, there are two kinks in Tigard’s plan that might also impact Tualatin. The first is that it’s possible not as much water would be available to pump from the Clackamas River as initially thought, so less of Tigard’s current water source would be available to Tualatin. The second issue is that Tigard’s water — though it comes from the same source — does not come through the Washington County Supply Line like Tualatin’s. So it wouldn’t be as simple a solution as leasing the extra capacity from TVWD would be.

Another option under the microscope is switching to Willamette River water. Before this could happen, the city would have to take it to a vote of the people for approval, due to a previous amendment in its charter.

“The big thing is we’re involved in the regional discussions to make sure we have a voice at the table now in case we want to make that choice later,” said Postema. “The choice may be we want to buy in and be an owner, or we may want to just be a wholesale customer like we are with Portland.”

The Water Supply Financial Evaluation was conducted because all of these options cost money — from sticking with Portland, to switching to the Willamette, to a combination of those two options — and switching to the Willamette was presumed to be more expensive based on the potential cost of building infrastructure.

“It think it’s incumbent upon us to say ‘Here are the needs. Here are the options, and here are the costs that go with those options,’” said Postema. “Then along with that, ‘Here’s the end product you will receive.’ After that, it’s just a personal preference.”

Study’s Findings

The study evaluated the options on a 30-year timetable, and admittedly met some challenges from the get-go, primarily because of all the different possibilities and factors. One challenge was the complexity of the Portland water rates, and unknowns such as whether more regulations are forthcoming or if the existing infrastructure might break down. Another challenge is that the partnerships with other agencies are dependent upon those agencies themselves and the myriad variables attached to each.

“The biggest challenge was everybody’s got a pretty good idea for the first five years. Because you’ve got your capital projects planned out, you know what the dollar amounts are,” said Postema. “The unknowns were basically: What happens in 20-25 years? What if treatment’s needed? What if something happens? What if regulations change?”

Over the 30-year period, staying with Portland is estimated to be cheaper than switching to the Willamette because of the initial investment of building the infrastructure, according to the study. Postema said that with a project of that size, it takes more than 30 years to pay it off, so if the study had extended as far as 40 or 50 years, the rates would have flattened out more. Even so, the predicted rates are relatively close together, and due to the number of variables, it’s possible that over 30 years they could change entirely for one reason or another.

“You never really and truly can cover the bases,” said Postema, explaining the possible variances with each option. “Everything’s got to be the best educated information you have available, worked into a formula that seems scientific, and you hope that you’re going to be close at the end of the day.”

The study also evaluated the financial impact of different hybrid options, and came out with similar conclusions. Assuming all goes well with Portland, it’s still the cheapest possible option. If the rates spike for some reason, such as changing filtering methods or large repairs, then over 30 years the cost between the options likely grows much closer, and in turn becomes harder to quantify and predict.

Postema said that the analysis will be complete by May, and that after that, the next steps are dependent upon what the city council wants to do.

“Tualatin has a very unique situation. It only resides here in Tualatin — it doesn’t reside anywhere else,” Postema said, noting all of Tualatin’s different options. The Willamette and Portland are “both really good water sources when you look at the end product, so I don’t see a downside with either one. I think they’re both upsides.”

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