John Michael Macbride joined the party along the Potomac River in western Montgomery County late Wednesday night. The hot, humid weather prompted some of the group of nine, including Macbride, to venture a swim.

Macbride, who police said had been drinking, was swept under the water's surface. Although his body has not been found, authorities presume he was swept away by the river's current and drowned.

Officials say Macbride, 25, of Northwest Washington, became the third drowning victim in the Potomac in the last 12 days. The two others, a 28-year-old Alexandria man whose body had been missing since June 19, and a 50-year-old woman, from Rockville, were discovered earlier this week.

Authorities said that the number of drownings is about average; the figures for this year are well below those for last, which was one of the river's deadliest.

Last year, the river was swollen by above average rainfall, and 36 people drowned.

Eight people have died so far this year along the 383 miles of the Potomac, which stretches from Garrett County, Md., to the Chesapeake Bay. Seven drowned in the stretch between the District and Allegany County, according to Sgt. Thomas McDonald of the D.C. police's Harbor Section, which supervises that portion of the river. "Looking at trends, the most dangerous time on the Potomac has passed us. Most accidents occur before the summer months," said Cpl. Ralph Parker, a spokesman for Maryland's Natural Resources Police.

Two people have died this year in the Natural Resources Police's jurisdiction, which presides over the river upstream from Montgomery County's Little Falls. Eighteen people died in that stretch last year.

Because of the rains, the river was declared unsafe 24 times last year during June and July. So far this year, the river has been judged unsafe once.

To avoid a repeat of the number of drownings last year, most of which occurred between April and August, the Maryland Department of Natural Resources has implemented a campaign to educate people on the dangers associated with the river.

The department now requires that people in moving vessels wear life jackets from Jan. 1 to June 30, Parker said.

Along with the mandatory life jackets, the campaign also distributed brochures on river hazards to area merchants, posted signs warning of the river's dangers, and developed a film on river safety.

"Education is necessary because this river is very deceptive," Parker said. "This river is unpredictable. The very stretch that may be safe today may not be safe tomorrow."