(CNN) -- Residents in an eastern North Dakota town were advised to leave their homes Tuesday in anticipation of more flooding in the already water-logged state.
The Sheyenne and Red rivers are rising again, causing concerns for more flooding in North Dakota.
Voluntary evacuations are "strongly recommended," in Valley City, North Dakota, said Mayor Mary Lee Nielson. Valley City is about 60 miles west of Fargo, which has experienced weeks of flooding.
The Sheyenne River, which runs through Valley City, has reached 20.5 feet, Nielson said. The first crest, expected on Thursday, should be about 22 feet, she said. Nielson has called for voluntary evacuations by 6 p.m. Wednesday.
A shelter has been established at a school in Buffalo, about 25 miles east of Valley City, she said. Valley City has a population of about 6,850.
About 450 National Guard troops from Minnesota and North Dakota were on the ground Tuesday to help with flooding. On Monday, the North Dakota National Guard dropped 1,000-pound sandbags into a breached dike on the Sheyenne. Crews had already repaired two other dikes.
Sandbags are still needed, Nielson said. A staging area has been set up at a building in Valley City.
Although crest predictions for the river were fluctuating Tuesday, the final crest is expected next week.
In Fargo, the Red River crested at nearly 41 feet on March 28, breaking a record that had held since 1897. But Fargo was also bracing for more flooding Tuesday, according to flood warnings issued by the National Weather Service. The Red River is expected to continue rising to a crest of 37 feet by Saturday, the weather service said.