The Army Corps of Engineers plans to install heavier warning buoys to discourage boaters headed for Little Falls dam on the Potomac where 22 people have drowned over the last 10 years and has devised a plan to make the dam less dangerous.

In a report released yesterday, the corps recommended a way -- apparently costing $1 million or more -- to break up the murderous undertow that has prompted local rescue workers to call the dam "the drowning machine." That project could be completed by next spring if it is approved by various officials, according to Rep. Frank R. Wolf (R-Va.).

The report was requested last May by Reps. Wolf and Michael D. Barnes (D-Md.), whose districts border the river, after five people -- a woman and four soldiers stationed at Fort Myer -- drowned at the dam. The boaters' raft had capsized in rain-swollen waters near the dam and they were unable to escape the turbulent current.

The dam, spanning the river two miles upstream from Chain Bridge, was built in conjunction with a drinking water intake for the District of Columbia.

Water cascades over it and down a sloped surface, hitting a ledge at the bottom. The arrangement creates a powerful backflow of water that loops in a continuous circle, trapping what ever falls into it.

Swimming is prohibited in the area, but novice boaters may be fooled by the seemingly calm waters.

One problem has been that buoys bearing warning signs are swept away each year. The new, heavier buoys to be placed in the river several hundred feet above the danger point are expected to stay in place.

Wolf said in a prepared statement that the nine new "Coast Guard-type" buoys "are being prepared for installation in the river as soon as the ice breaks up." The 8-by-3-foot buoys, attached to 3,000-pound weights, should be in place in about two weeks, he said.

"The buoys are going to help," Wolf said, "but the real solution will be the modification of the dam . . . . "

The corps recommends sinking bags filled with grout -- a cement-like material -- to slow the rush of water at the dam and prevent the turbulance.

Design of the project and installation of the bags will cost "probably over a million dollars, maybe two," Wolf said.

He said that "next we will meet with the Park Service, local jurisdictions and rescuers and let them look at the corps' recommendations. If there is a consensus, Rep. Barnes and I will work together to find the money.

"The modifications should be completed by April or May of next year, around the time when we usually have tragedies" at the dam, he said.

The size of the warning signs in the river was increased last year after Wolf and Barnes called a meeting with local officials, rescue workers and the Corps of Engineers, which built and operates the dam.

The corps then conducted a study, building a hydraulic model of the dam at its Waterways Experiment Station in Vicksburg, Miss., to test several possible modifications. The corps is now preparing a cost estimate of the grout-filled bag project.