Elaine Seager, Terrain Water quality in the Tully, Johnstone, Russell and Mulgrave freshwater rivers and estuaries continues to be in ‘good’ overall condition, according to the latest Wet Tropics Report Card (July 2018-June 2019).
The grades are an average across the entire year and are an assessment of the condition of waterway health – for example, the condition of the water supporting fish.
By contrast, the Reef Report Card is based on an estimate of the quantity of pollutants going to the reef.
Wet Tropics Waterways Chair Professor Steve Turton said the underlying scores reflect the pressure put on waterways by the recordbreaking dry periods followed by extreme flood events in 2018-19.
“Climate variability and heavy rainfall are a feature of the Wet Tropics, but this was the first year since we launched the Report Card in 2016 that we’ve been able to see the impact of a typical wet season,” Mr Turton said.
High concentrations of suspended nitrogen and phosphorus were recorded near river mouths of the Tully, Russell and Mulgrave during and after flood events. Scores for inshore water quality were the lowest in five years. The lowest water quality score for the Tully, Russell and Mulgrave is for dissolved inorganic nitrogen (DIN), although the Tully and Russell basins improved their DIN scores from ‘poor’ to ‘moderate’. The Johnstone is scored ‘good’ for DIN. Pesticide scores were graded ‘good’ across the board.