Study of water quality in the Derwent reveals rise in nutrient levels near New Norfolk

WATER quality results showing the health of the Derwent River have been revealed after a two-year monitoring program.

Ursula Taylor of the Derwent Estuary Program with a water sample in relation to a two year monitoring program of nutrients in the upper estuary of the Derwent River. Picture: NIKKI DAVIS-JONES

FINDINGS from a two-year monitoring program of the Derwent River’s water quality will help researchers to better monitor the condition of the estuary.

The Derwent Estuary Program’s research trial focused on nutrients, sediments and other standard physio-chemical parameters to better document changes in catchment water quality conditions.

Monthly water tests were conducted across 14 sites along the Derwent between September 2015 and August 2017.

DIRTY SECRETS OF HOBART’S RIVER DERWENT REVEALED

Derwent Estuary Program chief executive Ursula Taylor said there was growing concern over the past five years about the river’s water quality due to nutrient enrichment and algal growth within the Derwent River catchment and upper Derwent estuary.

Ms Taylor said the two-year monitoring program confirmed a trend of increasing nutrients within the river.

“We’ve noticed over the past five years there is an increase of nutrients in the water, particularly around the New Norfolk region,” she said.

“This is likely due to multiple sources including an expansion of industry and population in the area.”

There is growing concern over water quality in the Derwent Estuary, particularly at New Norfolk.

The trial found nutrients are largely derived from aquaculture in summer and agricultural sources during winter months.

Ms Taylor said the monitoring program didn’t confirm whether the Derwent was in an overall good or bad state, but she said river nutrients need to be lowered.

“Based on the report recommendations, our next steps will involve working with our stakeholders, including representatives of aquaculture and agriculture, to identify immediate actions to reduce nutrients in the river,” Ms Taylor said.

“With multiple problems comes multiple solutions and it could be as simple as adjusting riparian zones and looking at the impact of fish hatcheries.

“Our focus is the health of the water, and the monitoring is something we want to continue to do in a positive sense.”