About 200 fish deaths have been found at Three Mile Creek in Wangaratta.
EPA officers visited the creek and will work with council to conduct further analysis into the potential causes of the fish death.
EPA has exploring the feasibility and practicality of addressing the clean up of the issue with other agencies.
Suspected fish deaths should be reported to the EPA Pollution Hotline on 1300 372 842. It is important that reporters record any observations of pollution that may be a cause.