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 diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.
Water quality in the Tully basin remained ‘good’ with the score increasing slightly from 64 in 2015-16 to 66.
Dissolved inorganic nitrogen (DIN) scored the lowest (41) and was graded ‘moderate’, with monthly median concentrations often not meeting guideline values. The filterable reactive phosphorus (FRP) indicator scored 79 and total suspended sediment (TSS), the indicator for sediment, scored 78, and both were graded ‘good’, with monthly median concentrations often meeting guideline values.
Using the ms-PAF method, pesticides received a medium risk category, with 94.6 % of species protected in the waterways of the Tully basin. This resulted in a pesticide grade of ‘moderate’ for the basin.
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 four longer-term indicator categories that are updated every four years: wetland extent, riparian extent (both to be updated for 2017-18), invasive weeds (to be updated for 2019-20), habitat modification (impoundment length (to be updated for 2018-19) and fish barrier indicators (in development)). The flow indicator for the Tully basin (reported annually) was introduced in 2016-17.
Changes in the habitat and hydrology index scores over the last three years are the result of the addition of indicators rather than changes in the indicator scores themselves.
The habitat and hydrology index increased from ‘moderate’ in 2015-16 to ‘good’ with the score rising from 57 to 61 due to the addition of the flow indicator.
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 59% loss of palustrine (freshwater) wetlands from pre-clear to 2013. These results reflect a high level of historic loss due to development. Wetland losses in future reporting periods will be minimal.
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 ‘good’ for flows during 2016-17. Flows in the Tully Basin were not substantially altered from predevelopment flows in their capacity to support the key ecological assets of water holes, low flow spawning fish, riffle habitats and fisheries production.
More information on the results of the flow indicator is available in the results technical report.
The fish index is currently under development and will be available in future report cards.
Further information on the methods used to produce the scores and grades and detailed results can be found here.