The salmon industry plans to build a pit capable of storing up to 4,000 tonnes of dead fish in the event of a mass mortality event on the west coast, but the local mayor has accused the industry of lying about council's support.

The chief executive of the Tasmanian Salmonid Growers Association (TSGA) conceded he was "picking up on the feeling from the council that the relationship has been stretched" and said the pit was one of a "range" of options.

The TSGA has submitted a Notice of Intent to the Environment Protection Authority (EPA) to build a temporary "mort holding facility" at the Aquaculture Hub just outside of Strahan, on Tasmania's west coast.

Last year the EPA advised the salmon industry to plan for the event of a major fish kill similar to when 270 tonnes of fish died in 2015.

The proposed temporary holding facility would be used in an emergency situation to store up to several thousands of tonnes of dead fish while arrangements are made for their disposal.

Preparation work has already begun at the site to build the holding facility.

A holding facility was assessed as the best option in the event of a large fish kill incident at Macquarie Harbour. ( West Coast Council )

The TSGA notice lists the different option of dealing with large volumes of dead fish.

The option of dumping at sea "requires a permit" under the federal Environmental Protection (Sea Dumping) Act, with burial considered an "unattractive option due to environmental impact concerns" and that there were "few large locations for burial of large amounts" of fish.

Burying the fish in landfill would require "many haulage trucks passing through Strahan and they would need to be lined to prevent leakage of mort fluids", the notice stated.

Composting presented issues of "odour and vermin", while the 700-kilometre round trip of transporting the several hundred thousands of tonnes of dead fish to the Triabunna fish by-products facility on the east coast was too far, with the processing of morts "not permitted by the EPA for biosecurity reasons" at Triabunna.

Incineration was assessed as prohibitive due to the 20-week wait time and in excess of $2 million cost of a suitably large incinerator.

The liquifying of the dead fish was a reasonable longer term option, but it was noted "there would need to be a market for the resulting silage".

Under the proposal's strategy to win support for the holding facility, "inconsistency of message" was a "significant risk", with "reacting to criticism" and "misinformation" considered "severe" risks to the project.

It also detailed the "odour level predictions" from such a facility, noting emissions have a "clear potential to cause nuisance some distance" from the facility.

There have been several mass fish deaths at Macquarie Harbour, on Tasmania's west coast. ( ABC News: Sophie Zoellner )

The West Coast Council offered a scathing assessment of the industry proposal, saying the TSGA lied about having the Council's "strong support".

In an open letter to the EPA, West Coast Mayor Phil Vickers said the claims by the TSGA were disappointing.

An image from the TSGA submission, detailing "odour" predictions from the site. ( West Coast Council )

Mayor Vickers wrote on July 4 that in his opinion, the statement by the TSGA that it had "worked closely with the West Coast Council" which it described as being "extremely supportive of the project, to ensure local community interests and concerns are understood and considered" could "only be described as false".

The TSGA declined an interview with the ABC but said in a statement that industry stakeholders were meeting with Council on Thursday to "detail a strategy for handling fish mortality events and is working with the Council on an effective waste management plan".

Between October 2017 and May 2018, 1.35 million salmon died in Macquarie Harbour. On one occasion, Petuna lost 55,000 fish in a day.

The sudden spike in fish deaths, combined with pressure on the state's waste management system during the fruit fly crisis, led the EPA to approve emergency measures for 20,000 fish to be buried in a landfill site on the West Coast rather than disposed of through the standard waste management.

Mayor Vickers said he understood the EPA's reasons for granting that approval but said it was the result of an ad hoc approach to environmental planning.

"Council is calling on the industry and EPA to stop entertaining piecemeal approaches to waste activities that have the potential to cause serious harm to our environment and to affect the community," he said.

Fish pit 'one of a range of options': TSGA

Dr Adam Main, CEO of TSGA, said the organisation would work on rebuilding relationships with the local council.

"I am picking up on the feeling from the council that the relationship has been stretched," Dr Main said.

"I can see there is an opportunity for the TSGA to reconnect with the council."

Dr Main said the TSGA was communicating with the West Coast Community Forum but conceded that information had not reached local councillors.

He said the pit was just one of myriad options being considered by the TSGA to respond to mass fish mortalities.

"The pit is part of a broader strategy that come out of the harbour that we can't take to market," he said.

"There are a range of options we can look at for utilising fish if they do die.

"It's something we don't expect to have to deal with but it is due diligence for the industry to ensure we have the right mechanisms in place to ensure we can deal with it well."