The main town centre in the Murray Basin is Cardwell which is located on the coast opposite Hinchinbrook Island and has a population of 1,176. There are several other localities including Kennedy, Bilyana and Carruchan, mainly located near the centre of the basin.
The Murray Basin varies from steep rainforest-covered mountains in the west, to a low-relief floodplain mostly developed for agriculture in the centre, with further remnant forest near the coast.
Major waterways include the Murray River, Dallachy Creek, Meunga Creek and Kennedy Creek, and numerous smaller coastal creeks drain into Hinchinbrook Channel. The sub-catchments discharge into several wetlands included in the Directory of (Nationally) Important Wetlands, and which include declared Queensland Fish Habitat Areas, seagrass meadows, and areas within the Great Barrier Reef World Heritage Area.
The Murray Basin has an area of 1,115 km2 and also has a high proportion of natural/minimal use lands (64%). The remaining area is comprised of 14% sugarcane, 10% forestry, 6% grazing, 1% bananas, 1% other crops, 1% urban and 4% other land uses.
The Murray Basin grade has remained ‘moderate’ and the score increased from 55 in the previous year to 59 in 2017-18.
The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.
A water quality score and grade cannot be provided for the Murray Basin in 2016-17 due to insufficient data. A new end of catchment water quality monitoring site is being established through the Paddock to Reef program, and the data is expected to be available for the Wet Tropics Report Card for the 2018-19 reporting period.
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 Murray Basin habitat and hydrology index scored 58 for 2017-18 and the grade remained ‘moderate’.
The habitat modification score of 100 (‘very good’) is comprised of an impoundment length score of 100 (‘very good’) indicating that less than 1% of the total length of the waterways with a stream order of 3 or higher are impounded by artificial structures.
The fish barrier indicator method is still being developed and will be available in future report cards.
Riparian extent for the Murray Basin scored 75 (‘good’) with 7.8% 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 19 (‘very poor’) with 53.5% loss of palustrine (freshwater) wetlands from pre-clear to 2017. Since 2013, 37.3 hectares of palustrine wetlands has been lost. These results include a high level of historic loss due to development.
The invasive weeds indicator scored 19 (‘very poor’) in the Murray Basin and represents major impacts of aquatic weeds within the Murray freshwater system. The Murray Basin was the lowest scoring basin in the Wet Tropics, with impacts from aquatic weeds including hymenachne (Hymenachne amplexicaulis), salvinia (Salvinia molesta), water hyacinth (Eichornia crassipes) and pond apple (Annona glabra).
The Murray Basin was graded as ‘good’ for flows during 2017-18. Flows in the Murray 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 flow indicator provides scores for each flow assessment site and this can be used to assess flows at more local scales.
The fish index is currently being rolled out for the basins in the Wet Tropics and will be available for the Murray Basin in upcoming report cards.