Herbert Basin

In the upper catchment of the Herbert Basin the main towns are Herberton (population 934) and Ravenshoe (population 1,442), which are located on the Atherton and Evelyn Tablelands.

The largest town in the Herbert Basin is Ingham, located in the lower catchment, with a population of 4,767.

The Herbert River starts 8km north-east of the town of Herberton and winds 340 km to its mouth 7km north of Halifax. Due to its diversity of landform and social communities, the basin is most easily divided into three sections.

The upper basin consists of the vast north-western section upstream of the Herbert River Falls and forms the most southern extent of the Atherton and Evelyn Tablelands. This area is highly utilised for cropping, especially potatoes and hay. The area closer to Innot Hot Springs is undergoing an expansion of cane, and dairy is continually reducing. There are also extensive grazing areas in the western area of the upper catchment – and much of the area was subject to historic alluvial tin mining.

The intermediate basin includes the Herbert River Gorge and consists mostly of National Parks, State Forests and other State Land, some within the Wet Tropics World Heritage Area.

The lower basin is the river delta or floodplain, and is characterised by alluvial soils and regular inundation from flooding. Many of the streams and tributaries discharge directly into Halifax Bay. The lower catchment is dominated by sugarcane and there is some irrigation in the southern-most area of the catchment.

The Herbert Basin has an area of 9,842 km2 and consists of 27% natural/minimal use lands, 56% grazing, 8% sugarcane, 4% forestry and 4% other land uses.

The Herbert Basin grade has remained ‘good’ and the score has remained 66 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.

Water quality

The water quality grade in 2017-18 for the Herbert Basin remained ‘good’ with the score decreasing to 71 in 2017-18 from 76 in the previous year. 

Dissolved inorganic nitrogen (DIN) scored the lowest (32) and was graded ‘poor, with monthly median concentrations frequently not meeting guideline values. The filterable reactive phosphorus (FRP) indicator scored 83 and total suspended solids (TSS), the indicator for sediment, scored 90. Both were graded ‘very good’, with most monthly median concentrations meeting guideline values.  

Pesticides for the Herbert Basin were graded 'good' and scored 66, equating to 96.1 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 Ingham, capturing 87% 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 Herbert Basin habitat and hydrology index scored 61 for 2017-18 and the grade improved from ‘moderate’ for 2016-17 to ‘good’. 

The habitat modification score of 92 (‘very good’) is comprised of an impoundment length score of 92 (‘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 Herbert Basin scored 85 (‘very good’) with 3.9% 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 20 (‘very poor’) with 51.9% loss of palustrine (freshwater) wetlands from pre-clear to 2017. Since 2013, 31.6 hectares of palustrine wetlands have been lost. These results include a high level of historic loss due to development. 

The invasive weeds indicator scored 19 (‘very poor’) in the Herbert Basin and represents major impacts of aquatic weeds within the Herbert freshwater system. The Herbert Basin was the second 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 Herbert Basin was graded as ‘very good’ for flows during 2017-18. Flows in the Herbert 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.  

The flow indicator provides scores for each flow assessment site and this can be used to assess flows at more local scales. 

Fish

The fish index is currently being rolled out for the basins in the Wet Tropics and will be available for the Herbert Basin in upcoming report cards.

See the detailed reports for further information on the methods used to produce the scores and grades and detailed results.