The results from the water sampling of Edith Creek near Smithton were inconclusive in determining the exact cause of eel deaths reported in February.
The deaths of approximately 25 eels were reported to the EPA. Officers collected water samples from Edith Creek and the samples were taken to the labs for further analysis.
EPA Director Alex Schaap said the eels had died some time before the EPA received reports of their death and it was not possible to collect specimens suitable for an autopsy due to the state of decay.
"Sustained warm weather and low water levels are likely to have contributed to elevated water temperatures and depressed oxygen levels in the creek at this time and this may have made eels more susceptible to other stressors," Mr. Schaap said.
"EPA investigations also discovered seepage from a factory wastewater sump into the creek – however the effect on the creek appears to have been quite localised and it is not possible to conclude with any confidence that this caused the eel deaths."
"The seepage appears to be associated with unexpected deterioration of concrete rather than any management failure and so the focus is on working with the company to ensure such problems do not occur again rather than upon imposing penalties. Immediate measures were put in place by the company to prevent further seepage and longer term remedial works will be undertaken."