The corps only knows about the ones who didn’t hear the warnings, or didn’t heed them.

On Friday afternoon, Ariel Cotuc Chaudjay, 17, of Duluth, drowned near Little Ridge Park in Forsyth County. Late Saturday afternoon, Dago Bento Mejia, 14, drowned near Bell’s Mill Bridge, off U.S. 129 north of Gainesville. Mejia was visiting from East Meadow, N.Y.

The two teens died in a similar manner, according to investigators. Each had been wading in a shallow area and suddenly slipped into a steep drop-off. Neither of the victims knew how to swim, nor were they wearing life jackets.

Lake Lanier’s designated swimming beaches have gradual slopes that are safer for swimmers. But with the lake level now 15 feet below full pool, all of the beaches are dry. If people want to swim, they must venture into parts of the lake where dangerous drop-offs are common.

The low lake level also may have contributed to two more deaths late Saturday night. Nine people, none of whom had a life jacket, were riding in a rented pontoon that got stuck on a sandbar near Port Royale Marina in Forsyth County.

Two men jumped overboard to try to dislodge the boat from the sandbar. Fighting a severe thunderstorm, they both slipped under water and did not resurface.

The victims were identified as Lung Mang, 21, and Tha Thang, 23, of Alpharetta. Their fellow passengers told investigators that the men did not know how to swim.

All four people who died in Lake Lanier over the holiday weekend fit the typical profile of drowning victims in recent years. They were male, in their teens or early 20s, did not have strong swimming skills, and came from an ethnic background where English was not their first language.

People in this demographic have always posed a challenge for the corps, because they generally aren’t consumers of newspapers and other mainstream media.

"We’re doing the best we can to reach as many people as we can," said Patrick Robbins, spokesman for the corps’ district office in Mobile. "We send messages out to all the Spanish-speaking media in the metro Atlanta area. But the Asian people don’t necessarily have media outlets we can get to. You can’t reach everybody. There’s a zillion dialects out there."

Lapina said just this year, the corps decided to add Spanish-language signs below the English-language signs at the beaches. The corps had resisted doing so for a long time, because visitors to Lanier come from all countries, not just Hispanic ones.

"Lake Lanier is such a melting pot," said Lapina, noting that in addition to Hispanic and Asian people, he often encounters visitors who come from former Soviet republics.

Another problem with the signs is that they are only at designated beaches. But swimming is permitted anywhere on Lanier, which has 790 miles of shoreline. It’s impossible to post warnings at every point where someone might decide to wade into the lake.

But Lanier is already at the lowest level it has ever been in early July, and with the drought worsening, it could drop several more feet before the recreation season ends.

With the lake in such a dangerous condition, is it possible that the corps could take an unprecedented step and ban swimming in Lanier until the water level improves?

No, according to Robbins. "We don’t have the authority to tell people they can’t swim at all in the lake," he said. "That would be up to the state."

But Georgia has no authority either. "We don’t cover the activity of swimming. We only have jurisdiction over boating," said Jennifer Barnes, spokeswoman for the DNR.

The DNR has a rule that every boat must carry a life jacket for each person on board. But Barnes said the state cannot enforce a similar rule for swimmers.

Lapina said there is one area where the corps does require life jackets for everyone, whether they’re fishing or swimming. That’s in the Chattahoochee River directly below Buford Dam, where sudden releases of water through the dam can be fatal.

"We issued more than 20 citations (for not wearing a life jacket) over the weekend," Lapina said. "But (the river) is a fairly confined space. It would be difficult to do that on the lake."

Robbins said it all comes down to personal responsibility. "People just need to wear a personal flotation device (life jacket)," he said. "That’s the most important thing. It would stop a lot of these drownings."

But with millions of visitors, many of whom are from low-income families, it may be unrealistic to expect that they’ll stop on their way to the lake and purchase or rent a life jacket for every person in their party.

Lapina said some of the corps parks now have life jacket loaner stations at the beaches. But the service is only available for children, and most of Lanier’s drowning victims have been adults.

Barnes said so far this year, Lanier has had three drownings and three boating fatalities. The two men who drowned Saturday night were classified as boating deaths, she said, because they drowned after jumping off the pontoon.

According to DNR records, in 2007 Lanier had a total of eight drownings and three boating fatalities. In 2006 there were seven drownings and two boating deaths.

2005 was the best year in recent times, with just three drownings and no boating fatalities. That summer, the economy was robust and the lake level was at normal full pool, so there was no shortage of visitors at Lanier.

Officials do not know why there were so few tragedies in 2005. They only wish they could replicate that success.