A three-year trial of real-time nutrient sensors across the Derwent catchment in Tasmania has demonstrated how continuous monitoring can transform understanding of nutrient sources, loads and variability – insights that are critical for improving and maintaining catchment health.
Led by the Derwent Estuary Program (DEP), the trial marked Tasmania’s first catchment-scale deployment of real-time nutrient analysers. Seven Eco Detection Ion-Q analyser instruments were installed at strategic sites across the catchment, creating a continuous nutrient monitoring network capable of detecting changes that traditional sampling regimes cannot.
The project has been recognised nationally, earning a finalist spot in the 2026 Australian Water Awards. For DEP CEO Ursula Taylor, the trial was as much about building shared understanding across a complex catchment as it was about testing new technology.
“The Derwent catchment makes up around one-fifth of Tasmania’s land mass, so bringing together everyone who uses and influences it is no small task,” Taylor said.
“Thanks to funding from the Ian Potter Foundation, TasWater, the University of Tasmania, EPA Tasmania, businesses and landholders, we were able to undertake a trial that showed real potential as an additional data source to inform how we collectively improve water quality in the Derwent catchment.”
Before the trial began, nutrient monitoring in the Derwent relied largely on grab sampling collected at multiple sites across the estuary and its tributaries. While valuable, this approach offered only snapshots in time.
“This was the first time we’d collected real-time dissolved nutrient data at this scale,” Taylor said. “Previously, we were relying on grab samples once a month. That gives you part of the picture, but it misses the rapid changes in dissolved nutrients that can occur over hours or days.”
The continuous data generated through the trial revealed short-duration nutrient spikes, seasonal patterns and cumulative loads that had previously gone undetected. This richer picture is particularly important, given the scale and diversity of the catchment, which includes agriculture, fish hatcheries, sewage and drinking water treatment plants, hydro-electric dams, towns and the city of Hobart.
“Catchments are inherently complex systems. When you’ve got a catchment as large and diverse as the Derwent, understanding how nutrients move through it – and how they ultimately reach the estuary – is essential,” Taylor said
The seven analysers were deliberately located to test the technology under real-world conditions and to capture influences from a range of land uses and point sources. Sites included river locations downstream of a paper mill, a fish hatchery and a sewage treatment plant, as well as other key tributaries contributing to nutrient loads in the estuary.
“We wanted to see how the sensors performed at different sites and under different pressures. That meant placing them where they could capture cumulative impacts, as well as localised changes associated with specific activities,” Taylor said.
This approach allowed DEP to begin building a clearer picture of dissolved nutrient loads entering the estuary and how those loads vary over time.
“What we ultimately need is an understanding of both total and dissolved nutrient load and where it’s coming from,” Taylor said. “This trial gave us a good foundation for that and what a nutrient budget for the Derwent catchment might look like.”
While the data itself was valuable, Taylor said one of the most significant outcomes of the trial was the way it brought catchment stakeholders together.
“The trial was a really good conversation starter. It helped people better understand what we’re dealing with across the catchment, and why managing nutrients is such a shared responsibility,” she said.
Taylor said DEP’s role is fundamentally about partnership.
“We’re about bringing people together around a common goal. And for most of the population, in their use and enjoyment of water, that goal often comes
down to health – whether that’s safe drinking water, healthy fish populations, or being able to swim and recreate in the river and estuary.”
Taylor noted that Default Guideline Values (DGV) for nutrients are often exceeded for parts of the Derwent catchment. These exceedances would not be captured by traditional grab sampling programs.
“That really highlights why understanding nutrient movement through the system matters. If we don’t understand how nutrients are behaving in the catchment, it’s hard to design effective actions to reduce loads and protect river and estuary health,” Taylor said.
As a first-of-its-kind deployment in Tasmania, the trial was never expected to be without challenges. Operating new technology in dynamic river environments inevitably raised issues around maintenance, performance and data interpretation.
“Any new technology comes with challenges. But the information that came out of this trial will help evolve the technology so it better meets the needs of catchment managers,” Taylor said.
Overall, the sensors proved particularly reliable at riverine sites, providing high-frequency data that complemented existing monitoring programs. The trial also helped clarify where improvements could be made, both in how sensors are deployed, how sensitive they need to be to pick up certain nutrient values and how their data is used.
“It was really valuable to see how the analysers performed at different locations. That kind of practical learning is essential if real-time monitoring is going to be scaled up in the future,” she said.
The value of higher-frequency nutrient data extended beyond environmental insights. For some catchment users, access to real-time information has the potential to deliver operational and cost benefits.
“Higher-frequency testing can help organisations like TasWater, the paper mill, and fish hatcheries better understand when they need to test, treat or clean infrastructure. That kind of information can save time and money, while also supporting better environmental outcomes,” Taylor said.
For DEP, the trial reinforced the organisation’s role in supporting evidence-based management of the Derwent catchment and estuary.
“We do a lot of monitoring and reporting. This trial strengthened our ability to contribute to the science that underpins how the estuary is managed,” Taylor said.
This article was originally published in this year’s edition of Current magazine. Look at the edition and more on Indigo by AWA.