Tests confirm nutrients rise

Concern at Derwent water quality

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.

Derwent Estuary Program CEO 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 in- crease 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.”

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 said river nutrients needed 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,” said Ms Taylor.

“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.