CLARENDON, Ark. (AP) -- Arkansans sandbagged their front doors and pumped out their flooded basements Wednesday as a historic crest on the White River moved downstream, and a flooding expert said the state will have to deal with high water for weeks.
Residents and county officials along the river's path in east-central Arkansas worried that the river flows would hit an already swollen Mississippi River on the state's eastern border and flow back into their cotton and wheat fields.
"I don't think anybody knows how much higher it's going to get," Monroe County resident Marlin Reeves said as overcast skies threatened rain. Forecasters predicted a 50 percent chance of showers and thunderstorms hitting the Arkansas prairie by Friday.
Heavy rains filled major rivers in northern Arkansas early last week, flooding communities as the water moved downstream. Two people remain missing after the storms.
Gov. Mike Beebe declared 39 counties - more than half the state - disaster areas, while President Bush issued a federal disaster declaration for 35 counties on Wednesday.
National Weather Service hydrologist Steve Bays said the high waters will continue to threaten communities in Arkansas for weeks.
The weather service expected the White River to crest over the weekend at 33.5 feet, 7 1/2 feet above flood stage and more than a foot higher than it was Wednesday afternoon.
But water will remain on some roads and highways and in some homes into mid-April, as well as cover cropland into May or beyond, Bays said.
"The river's going to be out of its banks for a prolonged period of time," Bays said.
Outside of Des Arc, water from the White River began springing up in new places Wednesday along a rural levee north of Interstate 40. The day before, volunteers used sandbags to hold back the "sand boils" - muddy springs that develop when water passes underneath the earthen barriers.
Loy Hamilton, area commander for the U.S. Army Corps of Engineers' effort on the White River, said workers on Wednesday put 50-gallon barrels on top of the teapot-size sand boils to build pressure to staunch the flow.
"Right now, they're all flowing clear, which is ideal," Hamilton said, explaining that seeing silt in the water would mean the levee is being degraded from beneath. "If you shut it off, it just forces it around to another hole."
The levee will remain under 24-hour watch as long as the waters remain high, Hamilton said.
At Maddox Bay in Monroe County, Reeves, 67, used a small tractor to pile sand in the front yard of his home along the old White River. In its present-day channel, the swollen river moved along the opposite side of a pine-covered island visible from Reeves' backyard. Already, river water flooded into other yards and homes down the gravel road from Reeves' house.
Sand that Reeves got several days ago filled six bags piled against his front door.
Monroe County Judge Larry Morris, chief administrator in the county of about 11,300 people, said he feared the flooding would cut off roads to the area.
The county printed yellow-and-red flyers to distribute to residents, urging them to leave or to have enough food to last "at LEAST two weeks."
Wheat farmers already were reporting damage from the water, Morris said.
Recent heavy rains also flooded parts of Ohio, Indiana, southern Illinois and wide areas of Missouri. The weather has been linked to at least 17 deaths.
In Missouri on Wednesday, the U.S. Army Corps of Engineers began a two-day release of extra water into the Missouri River to help an endangered fish. State leaders wanted the release stopped, citing a risk of more flooding, and after losing a court effort to stop it they asked President Bush to step in.
The White House said the corps is complying with a long-standing supervised plan and is monitoring weather and river conditions closely. It said the corps would not have conducted the release if it endangered the public.
Meanwhile, the Mississippi River was rising more slowly than had been forecast at Vicksburg, Miss.
The Lower Mississippi River Forecast Center had expected the river to reach flood stage of 43 feet by Wednesday, but its latest prediction is that it will happen Saturday. The latest crest prediction is 45 1/2 feet on April 4, down from an earlier forecast of 46 feet.
Some areas of Vicksburg and Warren County already are taking on water, and others will flood if the crest forecast proves correct.