Last week, TasWater told The Examiner that no sewerage maintenance had been carried out in the region in the past month.

The statement came after TasWater was asked whether a sewerage leak could have contributed to the death of thousands of bream in the Scamander River on June 26.

"There have been no cleaning processes undertaken with sewerage pipes," a TasWater spokesman told The Examiner.

"Yes, we are confident [the deaths are not] related to sewer spills or sewerage maintenance."

Several phone calls from confused and annoyed Scamander residents refuted TasWater's comments, however, and last week, one caller supplied The Examiner with a copy of a letter (pictured) that outlined the water company's intentions to carry out sewerage pipe maintenance on June 15, 16 and 17.

Last week, a TasWater spokesman said a company contracted by TasWater had mailed out the letters to residents without TasWater's knowledge.

The company again denied any involvement in the mass fish death.

"Regrettably, the contractor's schedule for the works was not clearly conveyed to those TasWater staff seeking the information in response to The Examiner questions," a spokesman said.

"Similar to the ice scouring works, TasWater does not believe it contributed to the fish deaths."

The Environmental Protection Authority is still investigating what caused the deaths and has upped its testing to include samples of an unknown white powder on the river banks.

"The EPA currently has no reason to believe that pollution is the cause of the fish deaths, based on the investigation to date," a spokeswoman said.

"Results of testing on the water samples taken from the Scamander River on Friday, 26 June should be available [this week], along with the results of testing on the white residue observed on substrate along the river edge exposed by the drop in water level."