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00000179-65ef-d8e2-a9ff-f5ef8dd70000In early October 2017, large cracks were spotted on the ground at Rattlesnake Ridge, a hillside about three miles south of Yakima, Washington. By January, the cracks had widened and emergency officials became concerned that a major landslide could imminent.Around 50 residents who lived on a small tract of land at the bottom of the hillside were evacuated and officials prepared for the worst.By the end of the month, geologists and engineers concluded that the landslide was a slow moving one and the risk of a major, catastrophic slide was low. Warning signs were taken down and residents were allowed to return to their homes.

Residents Weigh Options, Government Scrambles To Prep For Rattlesnake Ridge Landslide

Near the town of Union Gap in South Central Washington state, a massive chunk of Rattlesnake Ridge is moving ever more quickly.

Geologists say it will likely cause a landslide. And when does come fully down, it could take out roads, infrastructure and in the worst-case scenario, dam up the Yakima River.

Now, nearby residents are weighing their grim options: Abandon house and home—or stay and risk their lives.

Reading the cracks

There are about 50 residents in 15 houses and trailer homes on a crescent of land wedged in a depression between Interstate 82 and the hillside that’s cracking near them. According to measurements taken since October by the state and its consultant, the land above this community and Interstate 82 is starting to move more rapidly.

Credit Google Maps
Google Maps
Around 50 residents live on a crescent of land wedged in a depression between Interstate 82 and Rattlesnake Ridge near Union Gap, Washington.

But there is some disagreement among experts on how big this slide will be.

Yakima County Emergency managers believe it could be a small and slow-moving slide and could actually stabilize itself.

Bruce Bjornstad, a well-known independent geologist who’s studied dozens of Columbia Basin landslides for about the last 20 years, called that “a baseless hunch.” He said this landslide looks very similar to another one—called the Toppenish Landslide—only 18 miles southeast in Yakima Valley.

Credit Bruce Bjornstad
A prehistoric landslide occurred along Toppenish Ridge under similar conditions that exist at Union Gap. At Toppenish Ridge a landslide about 0.1 sq. mi in area moved rapidly carrying a wall of debris out onto the floor of the Yakima Valley. After coming to rest, the landslide debris appears to have displaced the river ~0.3 mile further out into the Yakima Valley.

“There have been other landslides on other ridges, similar to what we have at Union Gap, that have released apparently very quickly and have produced landslides and debris that have moved out at least a quarter to a third of a mile out into the valley floor,” Bjornstad said. “And that potentially, if it happened near the Yakima River could dam up the river.”

Further, Bjornstad said where there are visible cracks in the land on Rattlesnake Ridge is just the start of where the basalt rock might calve off. He said landslides typically follow a curved line and the debris flows away from that. So what’s visible is only a small part of the picture of what might let go off this slope.

“If you project that crack to the south and north where you can’t see it yet, but it could develop over time as it continues to move -- that crack is going to let the land slide to the west towards the other side of Union Gap and that could potentially block the river, and definitely take out the freeway,” Bjornstad said.

Credit Bruce Bjornstad

And he said the landslide isn’t going to stabilize or go away. It’s just a matter of time before it all comes down.

Bjornstad added that if he were to travel past Union Gap on I-82, “I think I would find an alternate route.”

Between rocks and a very hard place

Janeth Solorio is a young mother who lives in the community. It’s a place of boarded up windows, broken furniture outside, and large chained German Shepherds and pit bulls.

“We have to move and we don’t have enough money,” she said. “And that’s why I’m worried—I’m alone with my son and I’m pregnant. So it’s not easy.”

Solorio and other residents said they live there because it’s so cheap. Most said they are farmworkers, but there’s not much work in the bitter cold. Apple branches and grape vines can be damaged at low temperatures. So there isn’t even pruning work right now.

And it’s too expensive to move.

But that is what firefighters and an emergency manager are asking them to do. There’s a church shelter, then a hotel stay for a month and a bit of extra cash to help them.

But only some have taken that advice.

Tony Castillo, one of the firefighters, said he hopes these residents will leave soon.

“What we’ve been told is that it could come down whenever,” he said. “It’s imminent. There is danger here.”

KUOW’s Liz Jones contributed to this report.

Anna King calls Richland, Washington home and loves unearthing great stories about people in the Northwest. She reports for the Northwest News Network from a studio at Washington State University, Tri-Cities. She covers the Mid-Columbia region, from nuclear reactors to Mexican rodeos.