SAN LUIS OBISPO, Calif. - San Luis Obispo County Sheriffs say nearly 6,000 marijuana plants were found growing off of Highway 101.

They say the plants were found last week halfway up the Cuesta Grade near a tributary for the San Luis Creek.

Sheriff's say one of the chemicals used to grow the plants is considered toxic and could have contaminated the creek.

"We don't know the results yet we took water samples last week we will know in about 10 days if its contaminated or not," says Tony Cipolla, Public Information Officer for San Luis Obispo County Sheriff's Department.

Cipolla says the plants were found on private property and an investigation indicates that they were part of a Mexican National cultivation operation. He says the San Luis Creek flows through many places throughout San Luis Obispo. Mission Plaza is one of those areas where you can find water flowing.

Currently, there are no signs up to indicate that there is testing of the water going on. Many kids can be found playing in the area.

"My kids like to come to the creek and refresh themselves they take their shoes off and they could get a disease from the pesticides these people used," says Jesus Fonseca.

He says his kids come here all the time to cool off. He also says he won't be bringing them back here anytime soon.

"It will probably be even longer than that until everything is clear," he says.

Sheriff's say the pesticide used to help grow the plants known as Carbofuran, was banned in 2006 by the the U.S Environmental Protection Agency, because it's toxic to humans and to wildlife.

"I have seen people currently playing and I used to play in this water as a kid and now I don't and it's gross now and there are things in the water you don't want to touch," says Maximillian Spearles.

Officials say they are discussing what to do if the test results come back positive and there is a toxic pesticide in the water.