Washington ? Missouri’s senators want President Bush to step into a dispute over water flows along the Missouri River, saying navigation along its drought-plagued cousin – the Mississippi River – is at stake.

“As waterway operations are beginning to re-emerge from impacts associated with Hurricane Katrina, another building threat to river transportation on the Mississippi River is developing,” Sens. Kit Bond and Jim Talent said in a letter to Bush. “We urge the administration to employ available resources to prevent another Mississippi River closure.”

The letter, sent Thursday, asks Bush to force the Army Corps of Engineers to release more water from reservoirs on the Missouri River, which provides more than half of the water for the Mississippi.

Under a river management plan the corps established last year, the lawmakers said, the corps would compound the problems downstream by imposing dramatic reductions of Missouri River flows starting in October.

They said that would reduce the Mississippi’s levels by 3 more feet, putting the river within 1 foot of closure to barge traffic just as the grain harvest reaches its peak.

Michele St. Martin, spokeswoman for the White House Council of Environmental Quality, said the letter is still under review.

Rep. Earl Pomeroy, D-N.D., said the letter fails to acknowledge record low water levels in northern states that threaten the water supply of residents in the Dakotas and Montana.

“It’s yet another effort to have the Missouri River system managed exclusively for the interests of downstream states,” Pomeroy said. “That’s not fair and it’s not legal, so I don’t expect this letter to go anywhere.”

And Sen. Byron Dorgan, D-N.D., said the request would harm upstream states; it ignores the impact of Hurricane Katrina and the potential impact of Hurricane Rita on the Mississippi River; and also ignores the fact that the Port of New Orleans is not operating and is unlikely to be operating at full capacity in the near future.

“Frankly, their request is a baffling one,” Dorgan said in a statement. “The last thing New Orleans and the downstream areas near the Gulf need right now is more water flowing down the Mississippi.”

The letter comes a month after the head of the Army Corps of Engineers rejected a similar request by Missouri Gov. Matt Blunt. John Paul Woodley, the assistant Army secretary who oversees the corps, said conditions did not warrant a special release of water to keep barges moving.

Woodley said emergency conditions did not exist on the river and said low water conditions could be addressed by dredging.

Missouri officials have criticized the corps’ river management plan, which shortens the navigation season on the Missouri by 48 days and calls for a “spring rise” to release water at specified times each year.

But a federal appeals court this year largely upheld the right of the Corps to manage the river.