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‘This thing could go right now’: Newport leaders search for solutions to aging and vulnerable dams

Two 50-year-old earthen dams are at high risk of failure — threatening homes, Highway 101 and the economic prospects of the largest tourism hub on the central coast.

NEWPORT, Ore. — On a recent warm spring day, bald eagles circled above the Big Creek Reservoir, northeast of Newport, as several anglers cast lazy lines into the deep green waters.

The tranquil scene belied a hidden danger, though. 

Just a few steps away, the dam that created the reservoir, and another one downstream, could suffer catastrophic failure in a moderate earthquake, or even spontaneously, due to their age and poor construction. 

“They're earthen dams, and they're just breaking down over time,” Newport Mayor Dean Sawyer said while looking out over the upper dam. “My biggest concern is that these things could go at any time, even right now, while we're sitting here.”

The two reservoirs together hold nearly 400 million gallons of water, and they're Newport’s sole sources of drinking water. The reservoirs also in a canyon above Highway 101 and a neighborhood of 40-50 homes, all of which could be wiped out by a dam failure. 

“That initial rush of water would take those homes out. They would have about a 30-second warning to get out of their houses there and they would not be able to do that unfortunately, and it would also take out Highway 101,” Sawyer said.

Seismic failure risks

The problems don’t lie within the dams themselves, but in the ground underneath them. The lower dam was built in 1951 and the upper in 1969, both constructed before engineers knew the full scope of seismic activity on Oregon’s coast. 

The Cascadia Subduction Zone, a 600-mile series of faults that runs off the coast from northern California to British Columbia, is capable of producing massive quakes, up to magnitude 9. 

But that's not the only earthquake risk — the dams also sit within about 60 miles of smaller, shallower fault lines, and they're vulnerable to even the more moderate quakes that those lines could unleash.

The dams were built on top of soft soil, not bedrock, and Newport city engineer Aaron Collett said. In an earthquake, the ground underneath the dams could give way, lowering the dams and causing water to spill over the top — a scenario that can destroy earthen dams very quickly.

“When the water starts to spill over the top of the earth and you end up with a failure point, then it just kind of erodes very quickly from the force of the water and it sounds kind of doom and gloom, but it seems like it almost is eating itself,” he said.

The dams don't even necessarily need an earthquake to fail, Collett said — crews recently discovered leaks in a 90-inch drain pipe in the upper dam. 

It's normal for some water to move through earthen dams, but the water moving through the drain pipe was carrying soil with it, and there was no way to know where that soil was coming from. Collett said that means there could be empty spots within the dam that would further compromise its integrity. 

“Instead of a very large earthquake, something much smaller could still cause a problem with the dam,” he said. “Or they could just fail spontaneously.” 

No other water sources

A failure wouldn’t just be catastrophic for the people living downstream of the dams. It would also leave the central coast’s largest economic hub and tourist destination without clean water for a lengthy recovery period. 

Emergency bottled water shipments have been used in other places where drinking water has become an issue, but Sawyer said that approach would only solve a small fraction of the problem if it happened in Newport.

“You can't live on bottled water for more than a couple of weeks,” he said. “You can't take a shower with bottled water, you can't take a bath, you can't wash your dishes, you can't wash your laundry.” 

Newport has a full-time population of about 10,000, Sawyer said, but that figure balloons to more than 30,000 at the height of tourism season. Roughly 2.5 million people visit the city every year, and all of them need water to drink. 

A loss of water supply would also severely hamper the city’s other major industries: fish processing along the Newport Harbor and the Rogue Ales brewery just across Yaquina Bay. 

“If this damn failed tomorrow, Newport would dry up real quick, probably within 6 to 8 months,” Sawyer said. “There's just no way you could bring in enough water to supply the fish plants, the hotels, the restaurants.” 

Cost of replacement

The city has come up with a plan to replace the two earthen dams with a single new one made of concrete, situated about halfway between where the two reservoirs now sit. The site was chosen because it’s one of the narrowest parts of the canyon, with the shortest drilling distance to solid bedrock. 

But dams aren’t cheap.  

“When we first started this, we were told it was $80 million to replace these two dams,” Sawyer said. “Now it's up probably $118 million, just because of increased costs with inflation.” 

Working with former Congressman Kurt Schrader, Sawyer was able to secure $60 million in federal funding, and he said Oregon Rep. David Gomberg helped the city get an additional $14 million in state lottery funds to go toward the project. 

That still leaves the city with a nearly $40 million gap to fill, and that’s far too much money to put on the city’s relatively small tax base, Sawyer said. 

“We're a town of 10,000, and there's no way that a town of 10,000 can afford $100 million. It's just impossible,” he said. “People would leave town if we had to raise their taxes to pay for it.”

And time isn’t on Newport's side. 

“We've also been told every year we don't build this project, the cost goes up by $5 million.” 

Ticking clock

Once they do get the money side figured out, city officials still face six to eight years of design, planning and construction. 

“I'm sitting here knowing that we have a safety driver to do this and that we aren't even going to start digging for three years, and then the construction is at least three more years,” Collett said.  

While they wait, Collett said crews have begun pumping grout into the leaking pipe, along with any other smaller fixes that can be done to prolong the life of the existing dams.  

“We are looking at a design to strengthen the pipe and buy ourselves enough time to design and build the new dam,” Collett said. 

Sawyer continues to employ a three-prong approach to raising funds: 

“Patience, persistence and being a pest,” he said. 

Until then, he and Collett both just continue to hope the unthinkable doesn’t come to pass. 

“If this fails and those houses go, those people will be gone, their houses will be gone, their livelihoods will be gone and that really that keeps me up at night,” Sawyer said. 

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