The body of Rohan Mathew may be lost to the waters of Lake Sidney Lanier.

Forsyth County fire officials on Thursday called off their diving efforts to find the 27-year-old Lawrenceville man's body, four days after he went under after sliding off a rented houseboat.

Capt. Jason Shivers estimated as many as 45 people from Forsyth, Dawson, Hall and Cherokee counties and the state Department of Natural Resources assisted in the search, which was focused on a square mile area near Six Mile Creek, directly east of Shady Grove Campground.

Shivers said the department's standard policy is to cease diving operations after three full days.

"Today's the last day," Shivers said Thursday. "After today, it will be limited to daily surface and shore searches, in case the body floats to the surface."

Drowning victims in Lake Lanier been found floating months after disappearing. In June 2008, the body of 46-year-old Broderick Bradford of Ellenwood was discovered by fishermen about 150 yards from the shore of Old Federal Park.

Bradford went missing two months earlier after falling from a personal watercraft near Aqualand Marina. Hall County divers spent eight full days over the course of a month searching for him before suspending diving efforts.

Shivers said Forsyth County's three-day policy was "fairly common with other agencies."

"You can only dedicate emergency resources to search for a body so long," Shivers said. "You have to use a common-sense approach and be mindful we're still stewards of tax dollars. And every time we put a man in the water, it's a risk as well."

Shivers described the conditions in the search area as "treacherous."

"When they get below 20 feet, it's zero visibility, and they're diving into a debris field," Shivers said.

Depths of the search area have been anywhere from 60 to 100 feet, with heavy vegetation, he said.

Shivers said Mathew was a native of India who worked in Atlanta. Mathew's close relatives still reside in India, though a cousin lives in Maryland, he said.

Mathew and nine others were on a rented houseboat Sunday afternoon in windy conditions when Mathew slid off a water slide and into the water without a life jacket, officials said. Witnesses told authorities that as the wind pulled the boat away from him, Mathew cried out for help before going under.

Shivers said Mathew could swim, but noted that the "conditions were horrible" on the lake Sunday.

Shivers said surface searches will continue "possibly for weeks."