Inland Tasmanian fish farm with no pollution limits - and few trout downstream

16/09/2024

An independent water scientist has expressed concern at a lack of pollution limits in the environmental licence for a fish farm that has discharged its wastewater into the South Esk River in northern Tasmania for more than a decade.

Water monitoring data submitted to the Environment Protection Authority (EPA) by Huon Aquaculture and released to Tasmanian Inquirer revealed elevated pollutant levels over the past year at the outfall below the Millybrook fish farm, between St Helens and Launceston in north east Tasmania. Test results for the water intake above the farm showed significantly lower levels of pollution.

Christine Coughanowr, an independent water scientist and former head of the government-backed Derwent Estuary Program, said the results were concerning. "The data clearly show a substantial increase in nutrient levels between the inlet and outlet from the fish farm, particularly for ammonia, phosphate and total phosphorus," she said.

She described specific conditions in the Millybrook farm environmental licence as "rudimentary at best". "For example, there are no limits on the tonnage of smolt produced, no monitoring requirements, and no annual reporting required to the EPA or to the public."

The EPA said there were not site-specific water quality standards for the farm, but the authority's 2021 default guideline values for the South Esk River catchment provided a broad benchmark.

However Coughanowr said the summertime emissions levels were far higher than those benchmark values. "Freshwater systems are particularly sensitive to elevated levels of bioavailable phosphorus, and during the January through March period, it appears that phosphate concentrations in the outlet were more than 15 times background levels and exceeded the default guideline value levels set for the South Esk River by 30 to more than 50 times," she said.

Geoff Baker, retired Queensland charter fishing skipper and keen trout fisherman, raised concerns after setting up camp in June to watch trout migrate up the South Esk River. He has visited Tasmania for 30 years and fished the river for more than a decade. He said two years ago there were very few fish, and this year there were none. Surprised at the lack of fish in the river, he went upstream and found that there was no insect life as well, which indicates poor water quality.

A spokesperson for the EPA said tighter licence conditions for the farm were likely to be completed this year. The change is not expected to involve a public consultation process as it is not legally required unless a fish farm licence has been unused for at least a decade.