The Daintree Basin has an area of 2,107km2 with a high proportion of protected areas (56% natural/minimal use lands and 32% forestry). The remaining area consists of 7% grazing, 2% sugarcane, 1% urban and 2% other.
Steep mountains and hills dominate this basin, with a narrow coastal plain. The coastal lowland fringe is characterised by mangrove wetlands, sandy beaches and inshore fringing reefs.
The majority of public and private land in the highlands is included in the Wet Tropics World Heritage Area, and there is a high level of tourism associated with the basins natural values.
The Daintree Basin grade has remained ‘very good’ and the score increased from 82 to 85 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 reporting for the Daintree Basin commenced in 2017-18 with monitoring conducted at the Lower Daintree end-of-catchment site. The site is located within the mid-estuary water type and is tidally influenced during base-flows. Consequently, freshwater basin condition assessment was restricted to high flow water quality data.
For 2019-20, water quality monitoring commenced at the lowland freshwater site further upstream on the Daintree River operated by Douglas Shire Council during base-flows and allows reporting for the whole year. Water quality scores are based on aquatic ecosystem guidelines for protection of freshwater systems and are not based on load reduction targets for the marine environment.
Water quality 2019-20 for the Daintree Basin scored 91 and remained ‘very good’.
The sediment score, comprised of the total suspended solids (TSS) indicator, was 90 (‘very good’) with monthly median concentrations of TSS mostly meeting the guideline values. The grade improved for 2019-20 and the basin experienced lower rainfall than the record rainfall events of 2018-19 that likely increased erosion within the catchment.
Nutrients were graded ‘very good’ scoring 86, with dissolved inorganic nitrogen (DIN) and filterable reactive phosphorus (FRP) monthly median concentrations mostly meeting guideline values. The grades for DIN and FRP remained ‘very good’.
Pesticides remained ‘very good’ and scored 98, equating to greater than 99 percent of species protected for the risk assessment metric.
Habitat and hydrology
The habitat and hydrology index is comprised of four longer-term indicator categories that are updated every four years: wetland extent, (updated for 2017-18), riparian extent (to be updated for 2020-21), instream habitat modification consisting of impoundment length (updated for 2018-19) and fish barrier indicators (in development), and invasive weeds (updated for 2019-20).
The annual scores for the habitat and hydrology index from 2014-15, 2015-16, 2016-17 represent the changes resulting from the addition of indicators and not changes in the indicator scores themselves, whilst the index scores for 2017-18 to 2019-20 included updates to the wetland extent indicator, impoundment length and invasive weeds indicators.
The Daintree Basin habitat and hydrology index remained ‘good’ with a score of 78.
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 was impounded by artificial structures.
Riparian extent for the Daintree Basin scored 99 (‘very good’) with 0.01% loss from pre-clear extent to 2013, due to the basin predominantly being in the World Heritage Area.
Wetland extent scored 60 (‘moderate’) with 15.8% loss of palustrine (freshwater) wetlands from pre-clear to 2017. There was no recorded loss of wetland area since the last assessment in 2013. These results reflect a historic loss, with the Daintree wetlands largely intact in the upper catchment.
The invasive weeds indicator scored 54 (‘moderate’) in the Daintree Basin and was the third highest scoring basin in the Wet Tropics region.
The flow indicator category could not be assessed for the Daintree Basin due to the lack of modelled pre-development flow, which is required for the analysis.
The fish barrier indicator method is still being developed and will be available in future report cards.
The fish index is currently being rolled out for the basins in the Wet Tropics and will be available for the Daintree Basin in upcoming report cards.