The Daintree Basin has an area of 2,107km2 with a high proportion of protected areas (56% natural/minimal use lands and 32% forestry). 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’ with the score increasing from 81 to 82 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. Water quality monitoring during the dry season will commence in 2019 at freshwater sites in the Daintree to provide reporting of base-flow periods in future report cards. Water quality scores are based on aquatic ecosystem guidelines for protection of freshwater ecosystems and are not based on load reduction targets for the marine environment.
Water quality for the Daintree Basin in 2018-19 remained 'good' with a score of 68 with monthly median concentrations of TSS often meeting the guideline values. The grade declined from 'very good' in 2017-18 and was probably affected by record rainfall events and increased erosion within the catchment.
Nutrients were graded ‘very good’ scoring 90 (up from 65), with dissolved inorganic nitrogen (DIN) and filterable reactive phosphorus (FRP) monthly median concentrations mostly meeting guideline values. The grade for both DIN and FRP increased from 'good' to 'very good' in 2018-19.
Pesticides were graded 'very good' and scored 85, equating to greater than 99% 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 2019-20), instream habitat modification consisting of impoundment length (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 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 and 2018-19 include the updated wetland extent indicator and impoundment length indicator. The Daintree Basin habitat and hydrology index remained at a score of 80 for 2018-19 and was graded ‘good’.
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. There was no change in impoundment length score for 2018-19.
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 62 (‘good’) in the Daintree Basin and was the second 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 pre-development modelled flow and flow assessment sites, which are required for the analysis.
The fish index will be available for all basins in next year's 2021 Report Card.