The main urban centre in the Tully Basin is the township of Tully, which is located inland and has a population of 2,436. Several localities, including Hull Heads, Tully Heads, and Mission Beach, are located on the coast.
The Tully Basin is steep in its upper areas which are primarily occupied by tropical rainforest and sclerophyll forests (largely in the Wet Tropics World Heritage Area), while the coastal floodplain has largely been cleared and drained for agricultural purposes.
Streams emerge from the coastal mountain range with high velocities and volumes resulting from rainfall events.
Koombooloomba Dam is located in the upper catchment and is used for power generation.
Wetlands listed in the Directory of (Nationally) Important Wetlands include Tully River-Murray River floodplains, Edmund Kennedy Wetlands and Licuala Palm Forest.
The Tully Basin has an area of 1,685 km2 and has a high proportion of natural/minimal use lands (75%). The remaining area is comprised of 12% sugarcane, 4% bananas, 5% grazing, 2% forestry, 1% other crops, 1% urban and 3% other land uses.
The Tully Basin grade has remained ‘good’ and the score has remained 64 since the previous year.
The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.
The water quality grade in 2017-18 for the Tully Basin remained ‘good’ with the score decreasing slightly from 66 in 2016-17 to 63 in the current reporting period.
Dissolved inorganic nitrogen (DIN) scored the lowest (39) and was graded ‘poor’, with monthly median concentrations frequently not meeting guideline values. The filterable reactive phosphorus (FRP) indicator scored 73 and total suspended sediment (TSS), the indicator for sediment, scored 80, and both were graded ‘good’, with monthly median concentrations often meeting guideline values.
Pesticides for the Tully Basin were graded 'moderate' and scored 54, equating to 93.4 percent of species protected for the risk assessment metric.
Water quality grades are based on aquatic ecosystem guidelines for protection of freshwater systems, and are not based on load reduction targets for the marine environment. The results are derived from the end of catchment monitoring site at Euramo, capturing 86% of the basin.
Habitat and hydrology
The habitat and hydrology index is comprised of the flow indicator category (updated annually) and four longer-term indicator categories that are updated every four years: wetland extent, (updated for 2017-18), riparian extent (to be updated for 2018-19), instream habitat modification consisting of impoundment length (to be updated for 2018-19) and fish barrier indicators (in development), and invasive weeds (to be updated for 2019-20).
The annual scores for habitat and hydrology index for 2015-16 and 2016-17 represented changes due to the addition of the invasive weeds and flow indicators, respectively, and not changes in the indicator scores themselves. The index score for 2017-18 includes the second year of reporting for the flow indicator and the updated wetland extent indicator. The Tully Basin habitat and hydrology index scored 65 for 2017-18 and the grade remained ‘good’.
The habitat modification score of 57 (‘moderate’) is comprised of the impoundment length score of 57 (‘moderate’) with 4.6 per cent of the total length of the waterways with a stream order of 3 or higher impounded by artificial structures. Koombooloomba Dam is the largest impoundment in the basin.
The fish barrier indicator method is still being developed and will be available in future report cards.
Riparian extent for the Tully Basin scored 72 (‘good’) with 9% loss from pre-clear extent to 2013. It is expected that the majority of loss is in the lowlands due to development and land use.
Wetland extent scored 17 (‘very poor’) with 57.8% loss of palustrine (freshwater) wetlands from pre-clear to 2017. Since 2013, an area of 6.6 hectares of palustrine wetlands has been lost. These results reflect a high level of historic loss due to development.
The invasive weeds indicator scored 81 (‘very good’) in the Tully Basin and represents low impacts of aquatic weeds within the Tully freshwater system. The Tully Basin was the highest scoring basin in the Wet Tropics for invasive weeds meaning that the impacts from aquatic weeds on waterway health is the lowest for the region.
The Tully Basin was graded as ‘very good’ for flows during 2017-18. Flows in the Tully Basin were not substantially altered from pre-development flows in their capacity to support the key ecological assets of water holes, low flow spawning fish, riffle habitats and fisheries production.
The fish index is currently being rolled out for the basins in the Wet Tropics and will be available for the Tully Basin in upcoming report cards.