Trinity Inlet

The area of the Trinity Inlet 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 14 km inland south of the inlet’s mouth and is approximately 8 km in width. It includes numerous tributaries that drain into Trinity Inlet.

Land use within and adjacent to the Trinity estuary area includes residential, industrial and commercial developments associated with the central business district of Cairns.

Trinity inlet includes the Port of Cairns which is a multi-purpose port that caters for bulk cargo cruise shipping, fishing vessels and reef passenger vessels. Land use adjacent to the smaller upstream tributaries is dominated by cropping (sugarcane) with some residential development.

The Trinity Inlet estuary grade remained ‘good’ in 2022-23 and the score remained 64.

Key results

• The water quality grade for Trinity Inlet remained ‘good’ and the score decreased from 73 to 69 since the previous year.
• Chlorophyll a remained ‘good’ and the score increased from 64 to 76.
• Dissolved inorganic nitrogen (DIN) and filterable reactive phosphorus (FRP) both declined from ‘very good’ to ‘good’.
• Dissolved oxygen declined from ‘moderate’ to ‘poor’.
• Estuarine seagrass condition improved from ‘poor’ to ‘moderate’ in Trinity Inlet and reached its highest score since 2015-16.
• Seagrass biomass increased at subtidal meadows whilst area cover at the intertidal meadow remained low.

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