Authorities are investigating the effects of salmon farm discharge into a greater Hobart drinking water catchment. 

The environment upstream of a salmon hatchery on Tasmania's Florentine River is pristine, but downstream it is an image of sludge, bacterial matting, and nutrients. The Florentine River feeds into greater Hobart's primary drinking supply. 

Tasmania’s Environment Protection Authority (EPA) says it is looking into whether the Salmon Enterprises of Tasmania (SALTAS) hatchery - an industry and state government-owned joint enterprise - has breached its licence. 

“Water sampling indicates nutrient loads from the fish farm may be contributing to the algal issues in the river,” an EPA spokesperson has told reporters.

The EPA says it is working with SALTAS on ways to address the problem. The authority has conducted preliminary testing that did not indicate concerns about Hobart's drinking water supplies, with further testing at the discharge site underway. 

Additionally, TasWater has committed to spend more than $240 million upgrading the Derwent's Bryn Estyn water treatment plant to address taste and odour problems posed by algae further up the system.  

ALTAS says it values healthy waterways and “continues to work towards that”.

“All operations are undertaken within the regulatory conditions, including monitoring programs and reporting,” a spokesperson said.