EPA Director, Catherine Murdoch, has set a Total Permissible Dissolved Nitrogen Output (TPDNO) of 48 tonnes until 31 July 2027 for Tassal's Marine Farming Lease 55 at Long Bay, Port Arthur.
This means Tassal must continue to operate within the 48-tonne annual nitrogen limit, which has been in place since October 2023. Tassal has operated below this limit over the past three production cycles.
Keeping the limit at its current level will allow another year of environmental monitoring to be collected. This will help the EPA determine whether the environmental improvements being seen are continuing under the current limit and inform the next review of the TPDNO.
Ms Murdoch said the decision is based on the latest available science and more than 10 years of environmental monitoring.
“The monitoring shows that water quality across the broader Port Arthur area has not declined, with key water quality trigger levels not exceeded since 2021.
Data also shows improvements in several environmental indicators, including measures of reef enrichment and algal growth," said Ms Murdoch.
Some localised environmental effects close to the fish farm, including increased nutrients and algal growth, are present, but monitoring shows these effects are not persistent when the lease is not stocked.
Ms Murdoch said the EPA will require further scientific investigations to better understand how nutrients move through Long Bay and Port Arthur, and the contribution from different nutrient sources.
“This work will be undertaken with research partners including the Institute for Marine and Antarctic Studies and CSIRO and will help inform the next review of the nitrogen limit."
The EPA will continue to closely monitor environmental conditions in Long Bay and use the best available science to inform future regulatory decisions.
Background
Further information on the TPDNO decision for Long Bay can be found here.
Published on:
1/09/2026