Gully and Stream Bank Erosion – Herbert Catchment

The primary goal of the Australian Government's Reef Trust Phase IV Herbert River Gully and Grazing Program is to reduce the fine sediment loads delivered to the Great Barrier Reef lagoon.

The Herbert catchment has been identified as one of the priority reef catchments to be targeted under this program. Terrain has begun working with grazing landholders in the Upper and Lower Herbert catchment to identify sites for remediation activities.

These will include earthworks to reshape gullies, fencing to keep stock away from stream banks, weed management, revegetation and changing grazing farming practices.

Why its important

Sediment is one of the major pollutants affecting the health of the Great Barrier Reef.

When fine sediment is suspended in water on the reef it blocks the sunlight from reaching the algae that photosynthesise the sunlight to gives coral its vibrant colours. The algae is dependent on sunlight for its survival.

In addition to coral, sea grasses also need sunlight to survive. Sediment can kill or damage sea grass beds, which also has a knock-on impact on mammals and fish that feed on them.

The three catchments responsible for the majority of fine sediment reaching the Great Barrier Reed are the Burdekin, Herbert and Fitzroy.

What causes sediment to reach the reef

Erosion of subsoil contributes approximately 90 per cent of the fine sediment load delivered to the Reef.

Most of this comes from gully and stream channels. Gully erosion contributes at least 40% and stream erosion about 30%. The rest comes from subsoil from rilling on hillslopes.

Gully erosion became a problem after the introduction of livestock grazing and other catchment disturbances between 1850–1900.

Gully erosion became extensive along drainage lines and in floodplain sediments adjacent to some large river channels while stream banks exposed to grazing and degradation of vegetation have been eroding at accelerated rates.

Another issue identified in the Herbert is leaking tailings dams from old mines. These contain super fine crushed rock, a waste by-product of mining. The integrity of some tailings dams have been compromised resulting in materials being discharged into the Herbert when it rains.

Who to contact

If you are a grazier in the Upper or Lower Herbert and you would like to find out more about this project, please contact Jen Mackenzie on 0438 206343 or jennifer.mackenzie@terrain.org.au.