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GUERNEVILLE, Calif. — Floodwaters that turned two Northern California communities into islands were expected to begin receding Thursday as a rain-engorged river finally peaked after swamping thousands of homes, businesses and other buildings.

The Russian River in the wine country north of San Francisco crested at more than 46 feet Wednesday night, Sonoma County officials said.

The river frequently floods in rainy weather but it hadn't reached that level for 25 years and wasn't expected to recede again until late Thursday night.

The estimated 2,000 buildings inundated by floodwaters were mainly in and around Guerneville, Khan said.

"Guerneville has essentially become an island," Khan said. The nearby town of Monte Rio also was isolated when roads leading to it were swamped.

No injuries were reported and by Wednesday night the rain had eased but about 3,500 people in two dozen river communities remained under evacuation orders.

In addition, two sewage treatment plants weren't working, leading to concerns about potential sewage spills, she added.

The Russian River has crested over flood stage and is expected to continue to rise to record levels and inundate the town of Guerneville. Justin Sullivan / Getty Images

The river was one of several in Northern California that was engorged by days of rain from western U.S. storms that also dumped heavy snow in the Sierra Nevada, throughout the Pacific Northwest and into Montana, where Gov. Steve Bullock signed an emergency order to help keep up the supply of heating fuel amid frigid temperatures.

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Two Amtrak trains together carrying nearly 300 passengers stopped and reversed directions because of an avalanche that closed railroad tracks in the Sierra Nevada.

In Idaho, the mountain town of Stanley became marooned Wednesday after all three highways leading to the town were closed because of drifting snow, avalanches and the risk of more slides.

Several areas in California set record-high rainfall totals, including nearby Santa Rosa, which had nearly 8 inches (20 centimeters) of rain in one day. The often-waterlogged Venado weather station 5 miles from Guerneville recorded more than 20 inches of rain in 48 hours.

Dozens of people were rescued from cars that became stranded Tuesday and early Wednesday after drivers tried to cross flooded roads.

Nina Sheehan, who is visiting from North Carolina, had to abandon her rental SUV after it got stuck in a flooded hotel parking lot.

"We made a decision to take the rental car through the waist-high water and we got two thirds of the way and then the car stalled," she said.

A kayaker paddles through a flooded neighborhood on Feb. 27, 2019 in Forestville, California. Justin Sullivan / Getty Images

Rhondell Rasmus had pulled to the side of a road too flooded to cross in Sebastopol in Sonoma County late Tuesday night and emergency dispatchers told her to wait for help. But just before dawn, she awoke to find the car was nearly submerged and she was out of gas.

"The water just came up so fast next to my car, it was crazy," she told the Press-Democrat newspaper of Santa Rosa.

She wound up in an emergency shelter, bringing with her a handbag, a backpack and a pair of rain boots.

In Guerneville, streets became seas of muddy brown water. Jeff Bridges, a hotel co-owner who is president of the Russian River Chamber of Commerce, spent the day canoeing through town and gave a ride to a couple and their dog who were stranded in a low-lying apartment.

Five people whose homes were flooded were bunking down at his two-bedroom home.

"We saw quite a few fish swimming by my front porch," he said.

Bridges said this flood was the fourth he's experienced in 33 years and the locals took the disaster calmly.

"It's the price you pay to live in paradise," he said. "Buffalo, New York puts up with blizzards. Miami and Houston put up with hurricanes...we have floods."

However, Bridges said it will take weeks to clean up his R3 Hotel, as he has done in past floods. More than 8 feet of water inundated the 23-room business.

"Anything that's been flooded you've got to rip it out, sanitize everything...and rebuild," he said, but added nonchalantly: "Everything's fixable."