It's the first time officials have been able to put a number on the scale of the massive fish kill, which prompted officials for nearly two weeks to warn people in southeast Georgia not to swim or fish in the river.
"I've worked on the Ogeechee for 16 years and I've never seen anything approach this fish kill," said Tim Barrett, a DNR fisheries supervisor who compiled the estimate. "This isn't like an obscure small creek that people don't fish. People love this river and they catch a lot of fish there."
He said the death toll was estimated from samples of dead fish counted at 30 points along the river, with a margin of error of plus or minus about 4,500 fish.
Aside from the overall number of fish, Barrett said he was alarmed by the diversity of species affected. Dead fish were collected from at least 18 different species including redbreast sunfish, largemouth bass, bluegill, black crappie and white catfish.
Environmentalists such as Dianna Wedincamp, the Ogeechee riverkeeper, say fishing along the affected stretch of river has been devastated.
"That's several generations worth of fish that we lost," said Dianna Wedincamp, the Ogeechee riverkeeper. "We've lost the recreational fishing for at least a year or two."
After hearing initial reports of masses of dead fish May 20, state wildlife officials found them floating or washed onto riverbanks along about 70 miles of the river from Screven County northeast of Statesboro, to western Chatham County near Savannah.
Barrett said the dead fish were all found downstream from an industrial plant on the river in Screven County, while none were discovered upstream from the plant. However, no agency has linked the manufacturer to the fish kill.
Lab tests determined the fish were killed by columnaris, a disease caused by common bacteria that doesn't normally infect fish unless they're weakened by poor water quality or other environmental stresses.
The federal Environmental Protection Agency tested water samples from the river and found ammonia, formaldehyde and hydrogen peroxide.
EPA scientists concluded there wasn't enough of any one of those chemicals in the water to sicken the fish. But all three chemicals mixed together along with unseasonably high water temperatures and river flows reduced by drought might have left fish vulnerable.
"These multiple factors may have weakened the fish enough to make them susceptible to disease," Sharon Thoms, an EPA scientist in Atlanta, wrote in a memo last week. "It may be impossible to ever know for certain exactly what happened."
Officials say reports of dead fish in the Ogeechee have slowed to a crawl and last Friday they declared the river safe for swimming and fishing.
Wedincamp and others who live and work along the Ogeechee River say they're worried authorities will give up without pinpointing what caused so many fish to die.
Meanwhile, Bill Eason is struggling to keep his kayak rental business open on the Ogeechee. He figures the fish kill cost him 170 customers and about $4,000 during what should be his busiest time of year.
He's started selling his canoes and kayaks just to make ends meet.
"I'm selling boats, doing everything I can do to stay alive. And nobody's calling," Eason said. "Everybody's scared to death of getting in the water."