E. coli contamination from a sewage discharge has prompted the closure of a six-mile stretch of the Chattahoochee River in Roswell, Georgia, ahead of the July 4th holiday weekend.

The river is closed from the Chattahoochee Nature Center to Johnson Ferry Road, according to a tweet from Chattahoochee Riverkeeper.

Jason Ulseth, a riverkeeper for the organization, told CNN that the contamination was found on Thursday at the bottom of the river bed. Portions of disintegrated toilet paper were seen floating in the area, Ulseth said.

Crews have been tracking and sampling the contamination for more than a week. The closed area of the river is where levels of E. Coli were the highest, Ulseth said.

Ulseth says it's difficult to determine when the closure will be lifted.

E. Coli is the common name for many strains of bacteria, most of which are harmless but some of which cause disease in humans. Some strains produce the Shiga toxin, which can cause stomach cramps, diarrhea and vomiting.