DAHLONEGA, Ga. (WXIA) -- It's not what anyone expected to find at Yahoola Creek Park, a place known for its babbling water and shady trees.

"This is the county park, the main park that we have. There's people here all the time. People wade in the creek," said Lumpkin County Manager Stan Kelley.

So when dead fish started coming ashore, the county took notice. Kelley says he immediately visited the park and noticed about 20 dead fish.

An 11Alive viewer wrote us after trying to fish at the park, to say he saw "hundreds and hundreds of dead fish floating down the river." The Department of Natural Resources say the number is actually in the thousands.

Both the Wildlife Resources and Environmental Protection Divisions are investigating, along with the state Agriculture Department.

"There's a good bit of agricultural activity, pesticides, herbicides that may be involved in that area, which is why Ag is involved," said Albert Langley, Director of Compliance for EPD.

Langley says so far, there's no obvious cause and only fish appeared to be affected. Whatever it was, is gone, which he says could make finding a cause even more difficult.

There are healthy fish now in the water and test results show it the creek has the proper oxygen levels and is clean. Investigators hope the fish themselves can offer clues. But toxicology results may not be back for another two weeks.

The county says the fish started dying near the discharge point for Dahlonega's Sewer treatment facility. But there's another creek that connects with the Yahoola, and investigators found dead fish along there too.

Still, the EPD says it's taking water samples to make sure nothing was erroneously discharged from the facility. It's also taking plant samples from along the creek. The county says the vegetation was treated with an herbicide by the power company about two weeks ago.

Langley says there is a chance the fish died from the heat, but says it could also have been an accident.

"Spilling some herbicide into the storm drain that ends up in the creek, killing fish, but it's a one time thing that they don't even know about it and won't be repeated," he explained.