Mulgrave Basin

The Mulgrave Basin contains the largest population centres in the region.

At the northern end of the basin is the city of Cairns (population in excess of 170,000) and the Trinity Inlet.

The Indigenous Yarrabah community with a population of approximately 3000 people is located on the coast to the east of Cairns.

The Port of Cairns occupies the lower end of Trinity Inlet and provides limited deep-water ship berthing.

The upper catchment is in the relatively undisturbed rainforest environments of the Bellenden Ker Range. A small portion of the upper Mulgrave is on the edge of the developed agricultural area of the Atherton Tableland.

The river floodplains and the lower river valley are dominated by sugarcane where the environment has been significantly modified with the loss of much of the original lowland rainforest.

The Mulgrave Basin grade has remained ‘good’ in 2022-23 and the score increased from 73 in the previous year to 74.

Key results

• The water quality grade for the Mulgrave Basin remained ‘good’ and the score increased from 69 in 2021-22 to 72.
• Dissolved inorganic nitrogen (DIN) improved from ‘poor’ to ‘moderate’, filterable reactive phosphorus (FRP) declined from ‘good’ to ‘moderate’, and sediment, comprised of the total suspended solids (TSS) indicator, improved from ‘good’ to ‘very good’.

The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.