BILLINGS, Mont. >> Devastating floodwaters that wiped out miles of roads and hundreds of bridges in Yellowstone National Park and swamped scores of homes in surrounding communities moved downstream Wednesday and threatened to cut off fresh drinking water to residents of Montana’s largest city.

Heavy weekend rains and melting mountain snow had the Yellowstone River flowing at a historically high level of 16 feet (4.9 meters) as it raced past Billings. The city gets its water from the river and was forced to shut down its treatment plant at about 9:30 a.m. because it can’t operate effectively with water levels that high.

Billings had a just a 24- to 36-hour supply of water and officials asked its 110,000 residents to conserve while expressing optimism that the river would drop quickly enough for the plant to resume operations before the supply ran out.

“None of us planned a 500-year flood event on the Yellowstone when we designed these facilities,” said Debi Meling, the city’s public works director.

The unprecedented and sudden flooding that raged through Yellowstone earlier this week drove all of the more than 10,000 visitors out of the nation’s oldest park, which remains closed. It damaged hundreds of homes in nearby communities, though remarkably no one was reported hurt or killed.

It also pushed a popular fishing river off course — possibly permanently — and may force roadways torn away by torrents of water to be rebuilt a safer distance away.

On Wednesday residents in Red Lodge, Montana, a gateway town to the park’s northern end, used shovels, wheelbarrows and a pump to clear thick mud and debris from a flooded home along the banks of Rock Creek.

“We thought we had it, and then a bridge went out. And it diverted the creek, and the water started rolling in the back, broke out a basement window and started filling up my basement,” Pat Ruzich said. “And then I quit. It was like, the water won.”

Park officials say the northern half of the park is likely to remain closed all summer, a devastating blow to the local economies that rely on tourism.

In Gardiner, Montana, businesses had just started really recovering from the tourism contraction wrought by the coronavirus pandemic, and were hoping for a good year as Yellowstone celebrates its 150th anniversary, said Bill Berg, a commissioner in Park County.

“It’s a Yellowstone town, and it lives and dies by tourism, and this is going to be a pretty big hit,” he said. “They’re looking to try to figure out how to hold things together.”

Meantime, as the waters recede, parks officials are turning their attention to the massive effort of rebuilding many miles of ruined roads and hundreds of washed-out bridges, many of them built for backcountry hikers. Yellowstone Superintendent Cam Sholly said assessment teams won’t be able to tally the damage until next week.

Kelly Goonan, an associate professor at Southern Utah University and an expert in national parks and recreation management, said rebuilding will be a long process.

“This is something we’re definitely going to feel the impacts of for the next several years,” Goonan said.

As the Yellowstone rebuild efforts get underway, rangers will have to consider the reality of the park’s altered landscape as well as potential future natural disasters.

“We certainly know that climate change is causing more natural disasters, more fires, bigger fires and more floods and bigger floods. These things are going to happen, and they’re going to happen probably a lot more intensely,” said Robert Manning, a retired University of Vermont professor of environment and natural resources. Officials may also be able to rebuild in a way that’s more ecologically sound than the roads and bridges built a decade or century ago, he said.

The rains hit just as area hotels filled up in recent weeks with summer tourists. More than 4 million visitors were tallied by the park last year. The wave of tourists doesn’t abate until fall, and June is typically one of Yellowstone’s busiest months.

Yellowstone officials are hopeful that next week they can reopen the southern half of the park, which includes Old Faithful geyser. Closure of the northern part of the park will keep visitors from features that include Tower Fall, Mammoth Hot Springs and the Lamar Valley, which is known for viewing wildlife such as bears and wolves

Still unresolved is how it will handle all the tourists when only half the park is open.

“One thing that we definitely know is that half the park cannot support all of the visitation,” Sholly said Tuesday. The park will likely implement some kind of reservation or timed-entry system to let people in without sending crowd sizes sky-high.