New tool for river mouth openings to have worldwide application

Mass fish kills in Victoria as a result of the opening of river mouths may be a thing of the past with the development of a major new estuary management tool.

Where rivers meet the sea, estuaries provide a protected place for birds, mammals, fish and shellfish to live, feed and reproduce. Estuarine habitats also benefit the economy by shoring up a range of industries such as commercial and recreational fishing and tourism.

At times in Victoria sand bars can block river entrances, leading to periodic flooding and damage to adjoining land and infrastructure. As a result sand bars have been removed to drain and reclaim land, sometimes with severe ecological consequences for estuarine environments such as wetlands.

Funding

In 2003 the Glenelg Hopkins Catchment Management Authority (CMA) received over $390,000 from the Australian Government to develop a tool that gives Victorian estuary managers certainty about whether or not to open up an estuary at a given time. The State Government has also provided support to the project.

Activities

In mid-2005 tens of thousands of fish and other freshwater creatures died when sand was illegally removed from where it was blocking the mouth of the Surry River, at Narrawong near Portland.

Glenelg Hopkins CMA Estuary Projects Coordinator Graeme Jeffery said decisions about estuary openings were highly complex, requiring consideration of the large variety of assets in an area.

"Artificial river openings can also have less obvious environmental impacts when fish eggs are flushed out to sea and habitat is lost for wading birds," Graeme said.

"On the other hand species such as the Short-finned Eel need to be able to move through open estuary mouths to the sea to spawn. So there are significant environmental benefits from river mouth openings that need to be considered."

The computer tool, Estuary Entrance Management Support System (EEMSS), allows users to record the socio-economic, cultural and environmental assets of an estuary and critical time-sensitive information such as water levels, water quality and bird numbers.

EEMSS then generates an impact assessment report, based on an assets-threats model, to compare opening with not opening at a range of water levels. The report will be vital for estuary managers to make scientifically justifiable decisions.

Set to be launched soon, EEMSS has been trialled at the Glenelg, Yambuk, Aire and Anglesea estuaries. The program will be used by all Victorian CMAs and may be applied by estuary managers in New South Wales, Western Australia and overseas in South Africa.

EEMSS was developed by Deakin University in collaboration with the Glenelg Hopkins and Corangamite CMAs, Parks Victoria, the Department of Sustainability and Environment, EPA Victoria and the Western Coastal Board.

More information

1. Graeme Jeffery, Glenelg Hopkins CMA Estuary Projects Coordinator: (03) 5571 2526 or g.jeffery@ghcma.vic.gov.au
2. Glenelg Hopkins CMA 

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