Investigators in Dallas are trying to determine what has caused the water in the Trinity River to turn reddish orange twice in one week, according to a Local 6 News report.

Authorities said the colored water was first reported the day the University of Texas played for the NCAA National Championship in the Rose Bowl. However, officials cannot determine if the two events are related, Local 6 News reported.

The orange water apparently came from treated sewage that was dumped back into the Trinity River.

Officials at the Trinity River Authority said they are not sure how it made it into the water supply.

The Environmental Agency in Texas has reassured nearby residents that the drinking water is safe.

Investigators said contaminating water is illegal and they will continue to search for the cause, according to the report.