Washington ? The Army Corps of Engineers refused late Tuesday to reduce water levels on the Missouri River despite a federal judge’s order to cut flows to protect endangered birds and fish.

The corps said the judge’s order, issued Saturday, conflicts with a federal court ruling last year that there must be enough water in the Missouri for barges to navigate and power plants to operate.

“It is impossible to simultaneously comply with the conflicting flow requirements obtained in the two orders,” the corps said in a statement.

Instead, the corps is opening talks with the Fish and Wildlife Service on a new “master manual” for the river’s flow to put into effect next year. A new plan was due last year but was postponed by the Bush administration.

The corps said the administration would ask Congress for $42 million next year for an unprecedented effort to restore the Missouri River ecosystem.

A spokesman for the conservation group American Rivers called the move “too little, too late.” A lawsuit by American Rivers and other groups prompted the judge’s order for low flows.

“The corps has no intention of changing the master manual or doing anything beneficial for the river,” said the spokesman, Chad Smith. “All of these actions are delay tactics ad nauseam.”

A federal court in Washington on Saturday ordered the low flows to comply with the Endangered Species Act. But a federal court in Nebraska ruled last year the river must have enough water for barges to navigate and power plants to operate.

At issue is an effort to restore the Missouri to a more natural spring rise and low summer flows to encourage fish spawning and bird nesting by threatened and endangered species.

Earlier Tuesday, U.S. District Judge Gladys Kessler in Washington denied a request by the Justice Department and the state of Nebraska to suspend her ruling ordering the low flows.

In her order, Kessler acknowledged barge companies would lose revenues, water quality may suffer and consumers may pay more for power this summer along the Missouri River. But she said that injury to wildlife — the least tern, piping plover and pallid sturgeon — would be irreparable without curtailing the Missouri’s flow.

The Justice Department said it would appeal the ruling.