Workers search for victims on Friday.  (Lindsey Wasson/Reuters)

It has been nearly a week since the devastating landslide in northwest Washington state. For much of that time, the slide’s toll has been oddly elusive. We know bad news is coming, we just don’t know when.

There is a long list of missing names, a death toll expected to grow and little movement on either front, leading to a situation where we know the destruction is widespread and catastrophic, but we can’t quite put it into the simple framework we often use after disasters and tragedies: How many people were lost?

We know the death toll — which was 17 as of Friday afternoon — will go up. “You’re going to see those numbers increase substantially,” Travis Hots, the Snohomish County District 21 fire chief, said during a news conference this week.

No survivor had been located since Saturday, the day of the slide. So as bad news has emerged from the area near Oso, Wash., so have the warnings about grim news to come. Officials have been saying for days that more bodies were going to be found. They haven’t been able to say when, only saying that worse news was coming.

A big part of why it has taken so long for these official numbers to change stems from the sheer difficulties faced by rescue workers trying to scour the field of debris, a search slowed and complicated by the nature of the disaster and poor weather. The slide area itself is incredibly tricky to navigate, authorities say. It’s gnarled and unstable, a square mile of mud, wreckage, broken wood, twisted pieces of cars and potentially dangerous fluids that have spilled (including gasoline and septic material).

“In areas, it’s like quicksand,” Hots said. “It’s very challenging debris to walk across.”

The slide area may also be as deep as 30 to 40 feet in some spots, the state’s Department of Natural Resources said.

“Our rescuers were sinking down to their thighs in the soft silt,” Bill Quistorf, the chief helicopter pilot for the Snohomish County Sheriff’s Office, said during a media briefing. “It was very difficult.”

A rescue worker looks over the debris pile Thursday. (Mark Mulligan/Reuters)

The slide also covers an unusually large stretch of land.

“Usually landslides when they fall, they’re kind of confined,” said Lynn Highland, a geographer with the U.S. Geological Survey’s National Landslide Information Center, who has studied landslides for 30 years. “This one had such a volume of material that it ran out on one side of the river, crossed it, dammed it and came out on the other side of the river.”

And there has been rain since Tuesday, something that also slows the search down, Hots said. “It’s a very challenging environment to work in and move around in,” he said.

Additional slides also remain a concern. Some crews were pulled out for several hours at one point until the area was determined to be stable, and geologists and other experts have had to keep an eye on it, said Steve Thomsen, the county’s public works director.

The list of missing names had swelled to 176 by Monday night, a number that was going to “drop dramatically” because it most likely included duplicate names, John Pennington, the county’s emergency management director, said in a briefing Tuesday. It had fallen to 90 as of Wednesday, but there were another 35 people reported missing whose status remained unclear.

“There is an awful amount of unknown,” Pennington said at one point this week.

Adding to the uncertainty: On Tuesday, workers believed they had located another eight bodies, but they weren’t officially added to the toll because they had to wait for the medical examiner’s office to clear them, Hots said. And it will take some time for the medical examiner’s office to catch up, at which point the numbers will increase, he said.

“We are going to do everything that we can with our capabilities to recover every single person,” Hots said. “That’s no guarantee that we’re going to get everybody, but we are going to do our very best to get everybody out of there.”

Washington National Guard rescue workers continue their search Friday. (Washington National Guard via Reuters)