CHATTANOOGA, TN (WRCB) -- A contractor who does work for TVA is defending the spraying of herbicide on Chickamauga Lake even though some residents and fisherman want stricter regulations of the chemicals used.

According to studies done over the years aqua services says hydrilla is absolutely a threat. It's not native to our region and can only be controlled not eliminated. At Chickamauga Lake the problem is getting worse.

"It's certainly going to inhibit recreation. It's an exotic species not supposed to be here. This vegetation will rapidly age this reservoir," says Troy Goldsby the VP of Aqua Services.

Goldsby says in four years hydrilla has spread from one small section of Chickamauga Lake to almost the entire perimeter.

Goldsby combats it by spraying residential area's at their request. Some have expressed concern with the chemicals he uses.

"The issue of whether or not it's safe was put to rest when the EPA said these products were safe to use in an aquatic environment," said Goldsby.

The area sprayed just can't be used for irrigation or drinking for five to seven days after spraying, and it's not mandatory to put up signs anymore, so it's common courtesy to let neighbors know.

That's where boaters and fisherman feel left in the dark.

Channel 3 outdoor contributor Chris Coleman and other fisherman have other issues with killing the vegetation.

"Aquatic vegetation is good for fishing, good for ducks and good for wildlife," said Coleman.

True to an extent says Goldsby. Fisherman claim hydrilla is good for fishing, but he says it's the exact opposite, not only is it a detriment to fishing but to the entire lake.

"On hot and cloudy days the plants take over all the oxygen in the area and you'll have a fish kill because of it. It harbors a type of bacteria that is carried to bald eagles and it kills them," he notes. "Mosquito infestation, carrying diseases. I just don't think you can take a temporary boost in bass fishing and justify the aging and death of a reservoir because that's what this leads to."