Moresby Estuary

The area of the Moresby 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 3.3 km north and 2 km south of the river mouth along the coastline and extends approximately 12 km inland. The area includes numerous tributaries that drain into the main river channel.

Land use within the Moresby estuary area is dominated by cropping and pond aquaculture with some residential development. The Moresby locality is on the western fringe of the estuary area. The Port of Mourilyan is located near the mouth of the estuary and exports raw sugar and molasses from a loader, wharf and handling facility.

The Moresby estuary grade declined from ‘good’ to ‘moderate’ in 2023-24, and the score decreased from 63 to 55, since the previous year.

Key results

• The water quality grade for Moresby declined from ‘good’ to ‘moderate’ and the score decreased from 71 to 55 since the previous year.

• The chlorophyll a grade, declined from ‘moderate’ to ‘very poor’ with monthly medians of chlorophyll a concentrations frequently exceeding guideline values. This represented substantially higher quantities of algae in the water column compared to the previous year.

• Turbidity declined from ‘very good’ to ‘good’ whilst the grades for the other water quality indicators were the same compared to the previous year.

• The mangrove condition of the Moresby estuary remained ‘very good’ whilst the score increased due to continued improvement since impacts associated with Severe Tropical Cyclone Yasi in 2011.

• Seagrass condition grade of ‘very poor’ was unchanged whilst the score declined from 14 to 9 since the previous year. However, some improvement in biomass has occurred at several meadows.

   

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