An initial investigation of the March 15 accident yielded no evidence of damage to the ditch, which crosses Georgia Highway 56 and empties into Rocky Creek.
Department officials who conducted a follow-up survey, however, found three dead fish Tuesday and notified Georgia’s Department of Natural Resources, said Allen Saxon, the department’s assistant director for facility operations.
State biologists who conducted a more extensive assessment recovered about 300 dead fish, Saxon said.
The spill occurred at the department’s Peach Orchard Road office when a pump failed to turn off after loading 12.5 percent bleach solution from a large tank into a smaller one.
Cleanup crews added a dechlorination agent to the storm drain and flushed the area with water to push the chemical through the system.