ST. LOUIS (AP) -- An Army Corps of Engineers plan calls for spending $8.4 billion to help restore the ecosystem of the Upper Mississippi River.

The corps also wants to spend up to $2.3 billion to expand locks and dams on the Mississippi. Details of both proposals were to be released Monday at a hearing in St. Louis.

Both projects, which would ultimately need funding from Congress, are part of the reconstituted Upper Mississippi River-Illinois Waterway Navigation Study, expected to guide management of the river for the next half century.

"Obviously, you're not going to restore the river back to its pre-lock-and-dam days," corps project manager Denny Lundberg told the St. Louis Post-Dispatch. "What we tried to do is identify problems that are there now, and try to resolve them going forward."

Three years ago, the corps scuttled a $1.5 billion navigation-only plan after a whistle-blower alleged the financial numbers behind the plan were phony.

The new proposals include restoring flood plains, building islands and creating backwater pools on the Upper Mississippi.

The river proposal is among the latest environmental restoration projects pitched by the corps nationwide. If approved, it would be second only to the $14 billion plan to save coastal Louisiana and slightly ahead of an $8 billion Everglades project.

Lt. Gen. Robert Flowers, chief of engineering for the corps, said recently that the corps was "transforming" to concentrate on developing "comprehensive, sustainable solutions" with an environmental focus.

"I'm convinced that for a nation to prosper it must provide a strong economy and protect its environment," Flowers told a meeting of the Corps Reform Network, a group of environmental activists and fiscal watchdogs during a meeting here. "It is not only possible, it is essential for the long-term health of our country."

In 2000, senior corps economist Don Sweeney in St. Louis blew the whistle on inflated numbers in the corps' $1.5 billion proposal to expand locks on the Upper Mississippi River. He said during the Corps Reform Network meeting last week that the navigation expansion plans were still unnecessary.

"It's even less justified now, because we have another four or five years of history, and there's no (barge) traffic growth," Sweeney said.

Most barge fleets are 1,100 feet long, while most of the existing locks are 600 feet long. The barges must break in half, using extra time and money, to pass through a lock. Anticipated increases in barge traffic helped justify the cost of improvements.

The corps originally proposed extending the length of five locks and building two new ones. The new proposals go even further, with the most ambitious alternative calling for five expanded locks and seven new ones.

Chris Brescia, president of the navigation group MARC 2000, said improvements were needed to keep barge traffic viable.

The corps also has proposed pumping billions into restoration projects sought by environmentalists. The most expensive alternative would restore about 83 percent of the ecological functions considered fixable by the corps.

Steve Ellis, water resources coordinator for Taxpayers for Common Sense, cautioned environmentalists at the Corps Reform Network meeting not to be dazzled by promises of big money.

"It's hard to have one hand out trying to change an agency, and another trying to get something from them," Ellis said.