Johnstone River Catchment

The Johnstone Catchment has an approximate area of 1680 km² and an annual runoff of 2.7 million megalitres. Coastal wetlands like mangroves, paperbark forests and swamps have reduced in area in the catchment by 60% since 1952. The health of the Johnstone waterway is adversely effected by sedimentation, loss of exotic flora and fauna, nutrients, chemicals, and organic material. Adjacent landuses have an influence on river health eg. the most frequently documented type of bank disturbance in a recent study was bank erosion through cattle access to the river.

A study on the riparian zone found that 116 sites (60 %) inspected were in poor or very poor condition, 39 sites (20 %) were in fair condition and 38 sites (20 %) were in good, very good or excellent condition. The study found that the degree of disturbance of the riparian vegetation varied and was related to adjacent land use.

Source: Johnstone River Catchment Management Association

Moresby River Catchment

The Moresby Catchment has an approximate area of 147 km² and the runoff from the catchment is estimated at 1 380 megalitres a year. Landuses in this catchment include: residential, agricultural, Mourilyan Port, and protected areas. The Moresby catchment has a large (27.5 %) portion of wetlands. Previous agricultural encroachment reduced the amount of wetlands but now 73 % are protected. Adjacent landuses have an indirect influence on stream habitat.

The main disturbances to the waterway health include wastewater discharge, water extraction, sand and gravel extraction, dredging, port development, and port operations. In contrast to the Johnstone Catchment, 55 % of sites had low disturbance or no disturbance, and 37 % of sites had high or extremely high disturbance.

Liverpool Creek Catchment

The Liverpool catchment covers some 311 km² and the tributaries include Kittabah, Meuribah, Jingu, Bombeeta, South Liverpool, Boundary and Cowley Creeks. The Johnstone Shire River Improvement Trust and the Johnstone River Catchment Management Association completed a River Action Plan in 2000.

This study identified typical problems in the systems as:

•   Weed infested point bars and overflow channels promoting further sedimentation, pressure on the opposite bank and migration of the stream across the floodplain.
•   Erosion threatening agricultural land, infrastructure and habitat.
•   Ground water seepage promoting mass bank failure.
•   Invasion of weeds threatening both terrestrial and aquatic habitats.
•   Infrastructure is under threat from the direct effects of erosion and is exacerbating erosion.
•   A high percentage of unsuccessful rehabilitation due to the use of inappropriate techniques.
•   The position of snags directing erosion forces onto banks, and threatening infrastructure.

The proposed rehabilitation works and management actions are:

•   Reinstate natural overflow channels.
•   Reduce pressure on outside bends.
•   Stabilise streambanks using 'soft' engineering approach.
•   Stabilise streambanks using 'hard' engineering.
•   Manage aggregate extraction.
•   Upgrade infrastructure