KANSAS CITY, Mo. - A controversial move to save an endangered fish by artificially raising water levels on the Missouri River will go forward despite a lawsuit to halt it, the Army Corps of Engineers said Monday.

Missouri Attorney General Jay Nixon filed suit Friday to stop the release of water from reservoirs along the upper Missouri River over worries it would flood farmland. The Corps of Engineers said it would go forth with its plan anyway, though it is unclear precisely when.

Paul Johnston, an Omaha, Neb.-based spokesman for the corps, said the release was dependent on water temperature, current and forecasted river flows and rain. It is to happen sometime before May 19.

The plan is the result of a 2003 Fish and Wildlife Service opinion that calls on the corps to protect the endangered pallid sturgeon by attempting to replicate the way melting mountain snow made the river rise each spring before dams were built.

The corps' plan had called for two spring rises this year, but the first was canceled because water levels in reservoirs feeding the river were too low. The corps said the reservoirs now have more than enough water.

There is wide dissent to artificially increasing the river level. Along the river's northern reaches, in Montana and the Dakotas, there are worries it will drain reservoirs too much to sustain normal boating and fishing interests. Downstream, there is concern crops could be flooded and barging could be sidetracked.

U.S. Rep. Ike Skelton, D-Mo., said he was disappointed with the corps' decision.

"The spring rise policy is bad for Missouri, with potentially devastating impacts for farmers who work the land along the river," he said.

Most environmental groups see the plan as a good way to protect the river's wildlife. And Brig. Gen. Gregg Martin, the corps' northwestern division commander, said all those concerns were considered.

"The corps worked closely with the Fish and Wildlife Service, basin tribes and stakeholders to develop a plan for spring pulses that benefits the fish with the least possible impact to other users of the river and reservoirs," he said.

Nixon did not immediately respond to a call seeking comment Monday.

The Missouri River stretches about 2,540 miles, making it the second-longest river in the country, behind the Mississippi, which it flows into north of St. Louis.