Minot, North Dakota (CNN) -- Waters rushed into an overflowing lake near Minot, North Dakota, faster and in greater amounts than expected Thursday, officials said, exacerbating the region's flood concerns.
But Minot Mayor Curt Zimbelman said Thursday that no new evacuations had been ordered, even though "the flows coming into Lake Darling are reaching the lake quicker and at a greater volume than predicted."
"Due to this, Lake Darling has increased its outflow," the mayor added -- increasing flooding in the flood-plain, though not to a point that it yet changes the "inundation zone."
Evacuations stand at about 12,000, according to Minot Fire Department Capt. Dean Lenertz. The mayor of Minot and the state's governor congratulated citizens on an organized and efficient evacuation thus far, with Gov. Jack Dalrymple saying it had "gone extremely well."
Sirens sounded in Minot early Wednesday afternoon, urging residents to abandon their homes in the face of major flooding. Water is already overtopping the city's dikes, which are leaking in some places.
Populated areas are seeing a couple inches of water on the ground at this time, and there is significant concern about dikes eroding, Lenertz said.
Dalrymple said that "all agencies are engaged" statewide in addressing the issue. He noted, for example, that workers with North Dakota's transportation department are moving 100,000 sandbags from Bismarck to the Minot area, and there are about 500 National Guard personnel on site.
The National Weather Service predicted record flooding as heavy rains and dam releases cause the river to swell at Minot.
The Souris River is expected to crest on Monday, two to three days earlier than had been forecast. Zimbelman said the river is expected to rise to a level five feet higher than any previously recorded.
Minot got some support from a hometown hero who was halfway around the world.
Actor Josh Duhamel, in Moscow for the "Transformers: Dark of the Moon" premiere, asked for donations to the local Red Cross. "My heart goes out to all the incredible people of Minot & surrounding areas," Duhamel said on his Twitter account.
The Souris River, which locals call "The Mouse" after the French translation of its name, flows through the center of town, and there are several homes and businesses along its low-lying banks.
Fearing the main levees would not hold back the water, emergency workers have been constructing local levees around a school and the Broadway Street Bridge, a main thoroughfare.
At least one of those had to be pushed back Thursday, said Zimbelman, eliminating Third street as a north-south access point through the city.
Residents appear to be heeding evacuation warnings. The evacuations zones are "pretty bare," Lenertz said.
In a sign they're taking the flooding seriously, some residents were pulling up carpets because they are easier to remove now than after their homes have been inundated with water.
Not everyone, however, was planning to evacuate.
Troy Erickson, 44, lives across the street from the perimeter of the evacuation zone and said he plans to ride out the flood.
His neighbor has a bucket loader and they have distributed several loads of sand and gravel around four houses, which are home to 13 people, he said. They have "lowered a couple hundred sandbags" on top of the mixture, he said.
"We've got more sandbags coming to have just in case we need to build it higher," said Erickson, a lifelong North Dakotan. "It if happens, it happens."
He said he is "a little bit" frightened because he's never been in this situation, though he was a toddler during the flood of 1969.
At the nearby Minot Air Force Base, about 1,000 members of the military and their families have been displaced by the rising waters in the city, according to Capt. Genieve David, a base spokeswoman. An emergency shelter has been set up on the base, with 50 people staying their overnight, the mayor said. An additional 221 people stayed at shelters run by the Red Cross.
Minot, in the north central part of the state, is the fourth-largest city in North Dakota. The evacuation order covers a third of its population, Fong said.
The river at Minot, which stood 1,555.6 feet above sea level early Thursday, is forecast to top the 1881 record of 1,558 feet early Friday and peak at 1562.5 feet early Monday.
The Souris River looks like a "U." It swoops in and out of North Dakota from Canada.
CNN's Jim Spellman, Ed Payne, Marlena Baldacci and Alta Spells contributed to this report.