National Guard engineers packed clay and dirt to build up an earthen dike Monday protecting this northwestern Minnesota town against the rising Marsh River.

Gov. Jesse Ventura sent in the Guard to help reinforce the dike, which was built after the catastrophic flood of 1997. Eighteen soldiers arrived Monday with two bulldozers and five dump trucks.

Volunteers stacked a double layer of sandbags on top to the dike to protect against the swollen river, which rose to within about two feet of the top before midday.

Tim Binstock, 17, said he had been "filling 'em, throwing 'em," since about 2:30 a.m. when a civil defense siren called out volunteers to help.

"We weren't really prepared for this, and it came all at once," Binstock said as he helped lay a line of sandbags along a ditch, where water had been seeping toward town.

The Marsh and Wild Rice rivers, swollen by heavy rains over the weekend, should crest by early Tuesday and then recede if no significant additional rain falls, said Kevin Ruud, Norman County's emergency director.

Mayor Jim Ellefson said the rivers' rise had slowed by early afternoon.

"I think that we're on top of things right now," Ellefson said.

Volunteers continued to haul trailers of sandbags to the south side of town, where a half-dozen homes were threatened and some residents evacuated voluntarily.

No new rain had fallen in the immediate area by early afternoon, but the skies remained overcast and thunderstorms were forecast for the broader region.

Ruud said the Wild Rice River had already crested about 10 miles upstream in Twin Valley, and the dikes seemed to be holding.

Norman County received more than 8 inches of rain Saturday night. Most of the area got another 1.5 inches of rain Sunday with some spots getting as much as 2 inches, said Gary Votaw, a meteorologist with the National Weather Service in Grand Forks, N.D.

Ada is vulnerable because it sits near the confluence of three waterways — the Wild Rice and Marsh rivers and a large drainage ditch — that act as catch basins for runoff from a large area to the east of town.

Crews cut through one dike in southwest Ada on Monday in an attempt to release water threatening a half-dozen homes in that area. The water had flowed into the neighborhood after a section of railroad bed belonging to the Minnesota Northern Railroad washed out. The homeowners there were told to get ready to leave, and some did leave, though no evacuations were immediately ordered.

Among those warned was Olga Merkens, who was in her home about 200 yards away from the washout when the mayor and a city council member came by around 9 a.m.

"They came banging on my door," Merkens said. "I thought they were going to bang my door off."

About two hours later, Merkens, 75, sat watching from her back porch as a small row of sandbags protected her patio and the front door to her house. Water had crept up to the base of her deck and was swirling past her yard.

"This is my home and I'm not leaving until the last second," she said.

Flooding is nothing new to the Ada area, which has been designated a federal disaster area at least 18 times in the past 35 years, Ruud said. In April 1997, Ada's 1,700 residents fled floodwaters in the middle of the night. The city's homes and businesses, as well as its high school and nursing home, were ruined.

Ruud said the water Monday was "right up there, if not higher" than 1997's levels.

The Wild Rice River doesn't have an official flood stage for Ada, but Ruud estimated it would be somewhere between 10 feet and 12 feet. He said the river was at 16.8 feet Monday morning, compared to about 8 feet 24 hours earlier.

By Monday morning, the only road still open into Ada was Highway 9 from the north. Numerous country roads and farm fields in the area were submerged.

"The biggest problem is all of this farmland is covered over and the roads have been cut in half, so no one can get anywhere," said U.S. Rep. Collin Peterson, D-Minn., who arrived Sunday to help. "A lot of crop is going to be ruined. And it might be too late to plant again."

American Crystal Sugar Co. agronomist Allan Cattanach said it would take another week to determine how the rains had affected the sugar beet crop. He said farmers were assessing their fields Monday and were hoping for cool, cloudy weather to keep the beet crop free of disease.