Federal officials increased water releases from two South Dakota dams on Saturday to make room for expected potentially heavy rains through early next week, adding to flooding woes along the Missouri River.
The annual "spring rise" on the Missouri already is expected to last deep into the soggy summer. The Missouri might start to crest soon, but it won't start to fall until August or later.
The U.S. Army Corps of Engineers water releases from five dams in North Dakota and South Dakota had already about doubled prior records to relieve reservoirs swollen by heavy winter snows and spring rainfall at the river's Montana headwaters.
With severe storms expected over the next four or five days that could dump up to 4 inches of rain in some areas, the Corps has started to increase flows by nearly 7 percent at the Oahe Dam above Pierre, South Dakota's capital, and the Big Bend Dam just downstream.
"It's going to be a widespread heavy rainfall event and obviously will have a big impact on the Missouri River Valley for the next four or five days," said Bruce Terry, a senior National Weather Service forecaster.
Terry said extensive rains of more than 1 inch are forecast from eastern Montana through southern North Dakota, all of South Dakota and northwestern Nebraska. Rainfall totals of 2 to 4-plus inches could be rather widespread for much of South Dakota and western Nebraska, he said.
Corps officials warned residents to ensure they were ready to pump stormwater out of the cities, over the levees and back into the river after the heavy rains.
The increased releases had South Dakota officials concerned about the strain on levees in Pierre and Fort Pierre nearby.
"The state is working with the Corps to ascertain the impact this will have, so that we can ensure the levees remain effective," South Dakota Governor Dennis Daugaard said.
"I am also very concerned about the effect this will have on private levees that were built relying on Corps information."
Weekend releases
The Corps plans to release 155,000 cubic feet per second from the Oahe and Big Bend dams on Saturday and 160,000 on Sunday, up from the roughly 150,000 it has been releasing.
It said about half the available capacity at Fort Randall would be taken up if the Oahe and Big Bend releases continued at the stepped up pace through mid-July and it has no immediate plans to increase releases from Gavins Point Dam.
Gavins Point is closely watched because the river flows freely from there for more than 800 miles straddling Iowa and Nebraska and through Missouri to the Mississippi River.
"We are on a razor's edge here and the rain will drive the releases," said Colonel Robert Ruch, the Corps' Omaha District commander.
Downstream from Gavins Point in affluent Dakota Dunes, contractors stockpiled materials to be ready if temporary levees there sustain another partial collapse. On Thursday, a partial collapse was discovered and repaired in Dakota Dunes.
The swollen Missouri River has flooded areas from Montana through Missouri, forcing residents to shore up protections and raise temporary levees around towns. Thousands of people have evacuated homes along the river, and more may need to go.
Pressure on levees
That constant pressure on the network of levees that protect farmland, roads, small towns and big cities from a river running well outside its banks is what worries folks downriver most as the high water heads south toward Kansas City and east toward St. Louis.
"The length of the flood will test levees like they've never been tested before," Missouri Gov. Jay Nixon said. "You're going to see levees which in essence may be tall enough, but not strong enough."
That isn't the only worry as the summer of 2011 shapes up as the worst since 1993, when a Missouri River swollen by weeks of rain over the north-central United States led to flooding that killed 32 people, damaged an estimated 100,000 homes and caused $15 billion in damage.
There's also the prospect of flooded fields in five states that will keep farmers from planting some crops and harvesting others. Highways covered with river water will be as much a headache for drivers as the cash-strapped state and counties that must pay to fix them. Barge operators — and those who rely on them — face big losses if the river remains closed to navigation.
And then there is the greatest unknown in a river valley with no more room for any more water.
"One of my biggest concerns is simply rain," Nixon said. "I know that's no big public policy pronouncement, but that's a big worry."
The Missouri was already running higher than normal last fall, when rains upriver combined with a heavy winter snow to fill the reservoirs in South Dakota and Montana and force the record-setting releases from dams the Army Corps of Engineers uses in most years to control the river's flow.
So far, the river has breached just three levees — a federally funded levee at Hamburg, Iowa; a small levee near Decatur, Neb.; and another small levee near Big Lake.
Army Corps officials believe levees that protect the Kansas City and St. Louis areas are safe. But Jud Kneuvean, chief of emergency management for the Kansas City Corps office, said the corps projects water levels could reach the top of two federal levees near St. Joseph that protect Rosencrans Air National Guard base. A federal levee near Glasgow could also see water near its top.
Farmland in danger
And many smaller levees protecting mostly agricultural land are in jeopardy between St. Joseph and Kansas City, Mo., and in central Missouri, according to the Corps. The flooding has already put hundreds of thousands of acres of farmland out of service, lost to wet ground, washed out crops and lost time in the fields.
Jon Hagler, director of the Missouri Department of Agriculture, said 570,000 acres in southeast Missouri were affected by the spring flooding along the Mississippi River. Another half-million acres are now in danger along the Missouri River, fertile land where corn and soybeans are already in the field.
"If it (flooding) stays through the summer, of course, that crop is gone," Hagler said.
The water washes away top soil, deposits sand and silt, and causes scourging of the land, potential problems that will need to be addressed after the water subsides, Hagler said. The financial impact on agriculture won't be known for some time, but Hagler said it could reach the hundreds of millions of dollars.
The flooding has already closed several roads in northwest Missouri, most prominently a section of Interstate 29 at Rock Port. Beth Wright, a state maintenance engineer for the Missouri Department of Transportation, warned that other highways close to the river and its backwaters could be shut down for weeks as the river rises.
MoDOT officials declined to speculate on what other roads or bridges could be affected but said drivers should be prepared for detours in northwest and central portions of the state through the end of summer.
Once the floodwaters recede, MoDOT will begin assessing the damage and the cost to repair it, spokeswoman Melissa Black said. For now, she said, the agency is focused on keeping roads and bridges open and keeping motorists safe.
It isn't just roads. Nixon worries that the airport at Rosencrans could be affected. Rail lines running near the river could be shut down.
The river itself is a vital part of transportation that could be lost for months. Already, a 261-mile stretch of the upper part of the Missouri River is closed to all navigation. As floodwaters creep into Missouri, the key stretch from Kansas City to St. Louis could close, too.
While a far smaller player in barge traffic than the Mississippi River, the Missouri is a vital conduit for shipping things like corn and soybeans, fertilizer, sand, gravel, asphalt and cement. Barge traffic on the Missouri has waned in recent decades, dropping from a peak of 3.3 million long-haul commercial tons in 1977 to 334,000 tons last year, according to the Corps of Engineers.
The biggest reason is the unpredictability of the Missouri's currents and water levels. Those factors only worsen as the river floods.
Lynn Muench of the American Waterways Operators, which represents the U.S. barge industry, said few barge operators are using the Missouri right now because of the flooding "and concerns of what could go wrong." Tugboat pilots steering the barges have a harder time maintaining control in high water that tends to move faster, and the wakes from passing barges may stress already fragile levees.
"Any kind of wake from us is not good," Muench said.