Barron Estuary

The area of the Barron estuary reporting zone can be defined by the pre-cleared extent of mangrove and saltmarsh remnant vegetation which is characterised by species that require periodic inundation of sea water. This area extends approximately 10.5 km north and 4.5 km south of the river mouth along the coastline and extends approximately 5.5 km inland. The area includes several tributaries that drain into the Barron River and coastal streams that drain directly into the sea.

The assessment area of riparian extent extends further up the river than the mangrove and salt marsh communities to the upper tidal limit and includes vegetation types that are more typical of freshwater environments.

Land use within and adjacent to the Barron estuary area is dominated by urban development. The northern beach suburbs of Machans Beach, Yorkeys Knob and Holloways beach, and the Cairns suburbs of Aeroglen, Cairns North and Whitfield overlay the estuary area.

Industries within the estuary area include the Cairns international and domestic airport, quarries, aquaculture and sugarcane.

The Barron estuary grade remained ‘moderate’ in 2023-24 and the score of 50 was the same as the previous year. The Barron River, which drains into the estuary, experienced extreme flooding in December following landfall of Severe Tropical Cyclone Jasper.

Key results

• The water quality grade for the Barron estuary remained ‘moderate’ and the score increased from 45 to 55. Annual condition of water quality was not adversely impacted by the extreme rainfall and flooding from Tropical Cyclone Jasper.
• Dissolved inorganic nitrogen (DIN) remained ‘poor’ whilst filterable reactive phosphorus (FRP) improve from ‘very poor’ to ‘poor’.
• Turbidity improved from ‘moderate’ to ‘good’, and the dissolved oxygen score improved substantially from 61 to 80 and the grade remained ‘good’.
• The habitat and hydrology index remained ‘moderate’ and decreased from 55 to 44 since the previous year, with both the flow indicator and mangrove condition indicator decreasing in score due to the severe weather events from Tropical Cyclone Jasper.
• The flow indicator for the Barron estuary declined substantially from ‘good’ to ‘poor’ mainly resulting from poorer scores for measures of flow variability due to above average rainfall, particularly the very heavy rainfall events during December.
• The condition of mangroves for the Barron estuary remained ‘good’ but declined in score due to impacts associated with flooding from Tropical Cyclone Jasper. Impacts from the flooding were particularly evident in the loss of shoreline habitat.

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