THE results of tests following a mass fish kill at Lake Wyangan have been released.
The Department of Primary Industries Fisheries stated there was insufficient evidence to determine a single, specific cause.
DPI Fisheries instead suggested it was a "strong possibility" the deaths were caused by the disturbance of sulfidic sediments from inflows to the lake.
Lake Wyangan North saw two significant inflows prior to the deaths, the first being several hundred ML of storm water from April 29 to May 4.
The second was a 242 ML "fill" of irrigation water which entered the lake over a six-day period, beginning on May 5.
Griffith Mayor John Dal Broi welcomed the findings of the report, adding that council will now work toward implementing solutions to the issues raised.
"Following the storm event in April, a cold snap dropped the water temperature over a period of two to three days significantly," Mr Dal Broi said.
"The storm event not only dropped the temperature of the water, but potentially disturbed the acid sulphate soil in the sediment on the lake bed, impacting oxygen levels and creating the condition which led to this tragic event.
"The report totally dismisses mismanagement on behalf of council and council staff."
Griffith City Council has committed $2 million for the construction of sedimentation ponds and wetlands, ensuring future water entering the lake is higher quality.
The report from DPI Fisheries also clarified that the kills were not caused by blue-green algae, localised pollution or pesticide.
"It's a beautiful lake, close to town," Mr Dal Broi said.
"I think we have to do all that we can to make sure that we maintain that lake, at a level that is safe to be used by the community."
The mass fish kill that occurred on May 23 and 24 saw thousands of species of dead native fish wash up on the shores of Lake Wyangan.
The lake was originally a quarry, which has led to large quantities of nutrient-loaded sediment accumulating over the years.
Griffith City Council are now working to control sediment inflow, improve water quality and discourage the growth of blue-green algae through water circulation.