Since the spring, Lake Lanier officials have been warning visitors about the lower water levels and the dangers they present.

The Fourth of July weekend provided a series of unfortunate object lessons. The lower lake level appears to have played a role in all four drowning deaths over the weekend, according to authorities.

With the drought drying up all of the U.S. Army Corps of Engineers' public swim areas, Lanier visitors are venturing farther into the lake to wade, drawing them closer to steep dropoffs that can prove deadly for non-swimmers.

"The dropoffs aren't new; they may just be in unfamiliar territory," said Michael Lapina, Lanier's chief park ranger with the corps. "As the water goes down, that's what exposes or makes the dropoff closer to the water's edge."

Over the three-day weekend, two teenagers drowned in separate incidents when they were wading and fell into deep water over their heads. Neither knew how to swim, authorities were told.

Two Alpharetta men died when they jumped into the lake to push their rented pontoon boat off of an exposed sandbar during a late night rainstorm.

Because of the lower lake level — about 15 feet below full — sandbars, tree stumps and debris are just below the surface of the water.

The dropoffs are part of the terrain of the rural area that filled with water with the completion of Buford Dam in 1956. At Buford Dam Park, Lapina said, the incline is pretty steep — "maybe 70, 85 degrees."

Lapina said a dropoff may also have been a factor in the first of the five drowning deaths this year at the lake, in May.

"You're wading in the shallow area, where normally the shallow area extends the entire bank," said Jennifer Barnes, a spokeswoman for the Georgia Department of Natural Resources. "You don't have as much area to wade as you think you do."

The DNR has drowning records for Lanier going back to 1999. That year, there were 11 drownings, still a record. There were seven in 2006, eight last year.

Lapina said visitors receive water safety information as they drive through park gatehouses.

Said Lapina, "People really have to take some responsibility for their actions."