Hinchinbrook Estuary

The area of the Hinchinbrook Channel 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 includes the length of the channel (approximately 45 km) and extends due south along the coastline from the southern mouth of the channel for approximately 20 km, the area also extends west on the mainland for approximately 10 km and east on Hinchinbrook Island for approximately 6 km.

The area has numerous coastal tributaries that drain into the channel from the mainland and from Hinchinbrook Island. The assessment area of riparian extent extends upstream of the Herbert River further than the mangrove and salt marsh communities to the upper tidal limit and includes vegetation types that are more typical of freshwater environments.

On Hinchinbrook Island the estuary area is all within National Park. The estuary area on the mainland is predominantly conservation use (Girrigun National Park) whilst land uses in the area include forestry and pond aquaculture with some cropping and residential development in the southern reaches on the mainland around the Herbert River.

The towns of Cardwell, located at the north of the channel, and Ingham, located to the south of the channel are both on the mainland. The Hinchinbrook Channel is listed in the Directory of (Nationally) Important Wetlands.

The Hinchinbrook Channel grade remained ‘good’ in 2023-24 and the score decreased from 72 in the previous year to 68.

Key results

• The water quality grade for Hinchinbrook Channel remained ‘good’, the score decreased from 73 to 63 since the previous year.

• The chlorophyll a grade, declined from ‘moderate’ to ‘poor’ and the score decreased from 46 to 28 since the previous year, with monthly medians of chlorophyll a concentrations often 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’ with the score decreasing from 90 to 71, whilst grades for the other indicators were unchanged compared to the previous year.

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