Waterways ‘good’ despite record-breaking weather

The majority of freshwater rivers and estuaries continue to be in ‘good’ or ‘very good’ condition, according to the latest 2020 Wet Tropics Report Card. However, record-breaking dry periods followed by extreme flood events did place some pressure on our waterways.

Wet Tropics Waterways Chair Professor Steve Turton said while high annual rainfall variability and extreme rainfall events are a feature of the Wet Tropics, the previous four years of Report Cards were reporting on near or below average annual rainfall.
“This is the first year since we launched the Wet Tropics Report Card in 2016 that we’ve been able to see the impact of a typical wet season. Higher runoff of sediments and pollutants are obviously associated with higher rainfall and this year we’ve been able to see the effects of significant flow events over extended periods of time,” he said.

“High concentrations of suspended nitrogen and phosphorus were recorded near river mouths during and after flood events and scores for inshore water quality were the lowest in five years. Significant damage was also caused to riverbanks in early 2019 and some of these are now being stabilised with engineered rock walls and revegetation to reduce the future risk of erosion and sediment loss.”

Released today, the 2020 Wet Tropics Report Card assesses the health of nine river basins from the Daintree to the Herbert. It is produced annually by Wet Tropics Waterways as an initiative of the Reef 2050 Plan, an Australian and Queensland Government framework for protecting and managing water quality flowing to the Great Barrier Reef lagoon.

The report card analyses scientific monitoring data from many organisations and is reviewed by an independent scientific panel made up of individuals with a range of expertise.

Professor Turton said that while increased nutrient, sediment and pesticide runoff was to be expected during high rainfall events, the community can help mitigate pollutant runoff by managing urban development and agricultural activities.

“Farmers across the region have been transitioning to land management practices with lower risk to water quality and their continued uptake of best management practices will further reduce pollutant runoff,” he said.

“However, waterway health is not just the responsibility of farmers, we all have a role to play.”

Professor Turton said Wet Tropics Waterways is currently working with the Office of the Great Barrier Reef to develop an urban stewardship framework to benchmark management practices being applied to urban development, stormwater management and sewage treatment activities.

“The new urban stewardship framework will be an important addition to the Report Card as it will help us to understand the contribution of urban communities to water quality in the Great Barrier Reef lagoon and how we can better manage them in future. Importantly, this process will address not only point sources such as wastewater treatment plants, but also urban land management practices and development projects,” he said.

“Next year we will also be reporting on the state of our fish populations across all Wet Tropics freshwater basins, with a focus on the diversity of native fish species and the presence of pest fish such as tilapia. We’ll be focusing on how local residents can do their bit for our waterways by correctly disposing of pet fish, aquarium plants and exotic fish species caught while fishing.”

Professor Turton said Wet Tropics Waterways would also continue to keep an eye on emerging issues such as microplastics and PFAS as it continues to collate data to track progress towards the Reef 2050 targets.

“It is important to focus on long-term trends; we are building a story about waterway health in our region, so we really need at least 10 years of data for the full story to emerge. So far, our overall grades are reasonably good - if they suddenly drop, we know we have a problem that needs managing.”

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