Thurmond Lake's falling water levels forced the closure Tuesday of Columbia County's six-lane "mega-ramp" at Wildwood Park.

"Right now it's unsafe for larger boats to use any of the ramps," said Barry Smith, the county's community and leisure services director.

The closure will affect the lake's dominant bass tournament venue and six major events scheduled there in September and October, including the area's inaugural ESPN Women's Bassmaster tour Sept. 18-20, Mr. Smith said.

No tournaments have been canceled, but organizers are being notified and efforts are under way to arrange alternate locations for anglers to launch.

"We've notified all the tournament owners of the conditions up here, and basically let them know we'd love to have them, but they may have to launch from other sites," he said.

Thurmond Lake's full pool is 330 feet above sea level.

On Tuesday, it had fallen to 315.5, and forecasts indicate it will continue to fall without heavy rains.

Wildwood's $1.1 million ramps, completed in 2003, have been closed several times because of low water, and extended twice in efforts to make them usable during droughts.

The most recent closing occurred last September, when the lake's pool fell to 322 feet above sea level.

The ramps reopened in January after a $450,000 renovation was completed.

"They were redesigned to work down to 315, and we're about there now," Mr. Smith said.

"You really need 3 feet of water on the ramps to launch safely, and after that it drops off severely."

The Women's Bassmaster event, with 85 boats, has no plans to change its schedule, BASS publicist Doug Grassian said when notified of the ramp's closure.

"We're certainly not going to cancel, but if we need to move to other ramps, we will do so, but we can still hold our weigh-ins at Wildwood."

Other tournaments scheduled this fall include: BFL this Saturday and Sunday with 100 boats; American Bass Anglers Sept. 13-14, with 45 boats; the Sept. 27 Sportsman's Festival and Wild Game Cookoff; the Mr. Clarks Hill tournament Oct. 4, with 40 boats; and a major FLW Tour event Oct. 22-25 with about 200 boats, Mr. Smith said.

The Corps of Engineers' Web site lists 18 ramps at the reservoir that remain usable, including Lake Springs, Amity and Cherokee.