The Musselshell River put a small central Montana town under an estimated 6 feet of water Thursday as the most recent bout of flooding to pound the water-logged state prompted authorities to declare emergencies in three more counties.
Meanwhile, relief workers planned to distribute drinking water, diapers and formula on the Crow Reservation, where dozens of families were left homeless by flooding from the Little Bighorn River.
In central Montana, water started coursing through Roundup in the early morning and had inundated the south side of the mining and agricultural town by 11 a.m., resident Cameron McCleary said.
The river was expected to crest between Friday and Sunday, authorities said. Between 30 and 35 homes were evacuated.
"The fire department came to houses and said, `Get out," McCleary said. "It's been coming in ever since and still rising."
More rain was forecast through the weekend as flood emergencies were announced in Jefferson, Sanders and Musselshell counties.
Authorities set up roadblocks around flood areas in Roundup, and closed roads leading to the town from the south and west. The only open route was from the east.
Musselshell County residents were urged to conserve water Thursday morning until emergency services could get an update on the situation.
Blaine Tulle, who helps his wife run the Pioneer Cafe and Roundup Video, said the flooding was the worst the town had seen since 1967. "It's a hell of a storm," he said.
To the south, residents and officials in Carbon, Yellowstone and Big Horn counties continued to pump water from hundreds of flooded basements. The Office of Public Assistance in Yellowstone County was closed for at least two days after it flooded.
Relief officials said drinking water, diapers and formula for infants would be distributed on the Crow Reservation over the next two days. Floodwaters have retreated on the reservation, but problems persist.
Along the Yellowstone River, Pompey's Pillar National Monument east of Billings was closed due to flood concerns. It was expected to reopen Friday.
In the small town of Joliet, authorities said they have been unable to break up debris trapped beneath a bridge along Rock Creek that has contributed to flooding. An estimated 160 homes had their basements or lower levels flooded when the creek rushed through town Wednesday.
"They have to wait to get that debris out until the water goes down," said Joliet volunteer fire chief Melvin Hoferer. "If we get some heavy rains, it would be a lot longer. It might be three or four more days."
In central Montana, the Petroleum County drinking water system was being threatened by rising waters.
At least 17 county roads were closed in Judith Basin County and many more in Petroleum County.
In western Montana, the National Weather Service reports water levels have reached flood stage in southeastern Missoula and Granite County. The service predicts water levels will rise above flood stage by Thursday afternoon and could continue to swell.
The eastbound lanes of Interstate 90 _ Montana's main east-west thoroughfare _ was closed from Livingston to Springdale, according to the Montana Department of Transportation. That's about a 20-mile stretch.
Water was running over the roadway in the area. Travelers were advised to use an alternative route through White Sulphur Springs and Harlowtown to link up again with the highway in Big Timber.
Dockery contributed from Helena.