Inshore Central

The northern boundary of the Central inshore reporting zone area extends north-east from Cape Grafton just south of Cairns to the offshore boundary and includes enclosed coastal, open coastal and mid-shelf waters.

The southern boundary of the Central zone extends due eastward from the mainland just south of the Moresby River at Double Point to the boundary of the offshore waters.

The major rivers discharging into the central zone are the Mulgrave River the Russell River and Johnstone River. The Moresby River discharges into the southern coastal area of the Central zone. Numerous smaller waterways drain coastal sub catchments that discharge into the Central zone.

Water quality in the Central zone is affected by plumes of sediments, nutrients and pesticides from rivers discharging directly into the zone but also from the plumes of southern rivers, particularly the Tully/Murray, which are carried north by prevailing currents.

The area includes Fitzroy Island to the north, the High Island Group some 12km north-east of Deeral, the Frankland Island group approximately 16 km due east of Deeral and Normanby Island located between the High Island group and the Frankland Island group. These islands provide fringing shallow water environments that support coral reef ecosystems.

The overall grade for the Central zone in 2022-23 remained ‘moderate’ to ‘good’ and the score increased from 60 to 63 since the previous year.

Key results

• The water quality grade in 2022-23 for the Central inshore zone remained ‘good’ and scored 71, increasing from 62 in 2021-22.
• Improvement in grades since the previous year occurred for total suspended solids (TSS), from ‘good’ to ‘very good’, and oxidised nitrogen (NOx), from ‘poor’ to ‘good’.
• Chlorophyll a, declined from ‘good’ to ‘moderate’ since the previous year.
• Pesticide monitoring and reporting re-commenced in 2022-23. High scores and a grade of ‘very good’ for pesticides, due to the very low pesticide toxicity risk, contributed to the increase of the water quality index score.
• The overall coral condition grade in 2022-23 for the Central inshore zone remained ‘moderate’ and the score decreased from 58 to 55.
• For coral the grade for cover remained ‘good’. Cover change declined after seven years of grading ‘good’ to ‘moderate’, however recovery of hard coral cover has continued at predicted rates. Macroalgae remained ‘moderate’ but the score decreased substantially from 59 to 44 due to very high cover at several reefs. 

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