The U.S. Army Corps of Engineers says an aquatic weed called hydrilla, first found in Thurmond Lake in 1995, now infests about 60 percent of the reservoir's 1,200-mile shoreline.
The Augusta Chronicle reports that Scott Hyatt, operations project manager at the lake, says the infestation probably started at a boat ramp.
The shoreline assessment found hydrilla in most major portions of the lake. The weed harbors a type of algae believed to produce a neurotoxin ingested by small birds known as coots that are a favorite food of bald eagles.
Experts say the condition, known as avian vacuolar myelinopathy, creates brain lesions that have killed at least 60 eagles at Thurmond Lake and many more elsewhere.
One option under review is the introduction of grass-eating carp.