Herbert Basin

In the upper catchment of the Herbert basin the main towns are Herberton (population 934) and Ravenshoe (population 1,442) and are located on the Atherton and Evelyn Tablelands. The largest town in the Herbert basin is Ingham, located in the lower catchment, and has 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.

Scroll down for further detailed results for each indicator group.

Grading

gradesa1

very good

gradesb1

good

gradesc1

moderate

gradesd1

poor

gradese1

very poor

insufficient data

Confidence surrounding the data used in the circle diagrams has been assessed using a multi-criteria framework.

confidence

Water quality

Hover over each segment for indicator scores and data confidence.

The overall water quality grade in 2015-16 for the Herbert basin is ‘good’.

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 one end of catchment monitoring site at Ingham, capturing 87% of the basin.

The sediment score is comprised of a total suspended solids (TSS) score of 90 (‘very good’) meaning that the annual median and at least 80% of monthly medians of TSS concentrations complied with guideline values.

Nutrients scored 75.0 (‘good’) in the Herbert basin, comprising of a DIN (dissolved inorganic nitrogen) score of 59.9 (‘moderate’) and FRP (filterable reactive phosphorus) score of 90 (‘very good’) meaning that the annual median and at least 80% of monthly medians of FRP concentrations complied with guideline values.

Using the ms-PAF method, pesticides received a low risk category with 1.8% of species affected in the waterways of the Herbert basin. This resulted in a pesticide grade of ‘good’ for the basin.

Compared to 2014-15 the water quality index for the Herbert basin remained ‘good’ and increased marginally from 79.0 to 80.7 with no change of indicator grades.

Habitat and hydrology

Hover over each segment for indicator scores and data confidence.

The overall habitat and hydrology grade for the Herbert basin in 2015-16 is ‘moderate’.

The habitat modification score of 92.1 (‘very good’) is comprised of an impoundment length score of 92.1 (‘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 85.0 (‘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 20.1 (‘very poor’) with 51.1% 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.

Habitat modification, riparian extent and wetland extent are updated every four years and have not changed since 2014-15. The data for riparian and wetland extent are due to be updated in 2018.

The invasive weeds indicator is new for the 2015-16 period and scored 19.6 (‘very poor’) in the Herbert basin.

The habitat and hydrology index score and grade differed between 2014-15 and 2015-16 due to the introduction of the invasive weeds indicator.

The method for the flow indicator is currently under development and will be available for future report cards.

Fish

Hover over each segment for indicator scores and data confidence.

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.