Task Force Wrestles With Alligator Weed

Sydney Morning Herald

Tuesday May 10, 1994

By JOHN STAPLETON

Alligator weed is the monster of all water weeds. It clogs channels, rivers and swamps, forming floating rafts strong enough to hold an adult.

Sheep have drowned after wandering out onto the plaited weed mats and then falling through a hole.

This year, Barren Box Swamp, a duck hunting and fishing reserve 15 kilometres from Griffith, had to be closed because of the weed. It was the first major outbreak west of the Divide.

The convener of the Alligator Weed Task Force, Mr Chris McIntosh, said if the outbreak was not controlled, it had the potential to threaten the inland river system.

The weed, from South America, was introduced accidentally in the 1940s. The most serious outbreaks are in the Fullerton Cove-Williamtown area north of Newcastle and the Georges River in Sydney.

At Barren Box Swamp, the NSW Department of Water Resources has been spraying non-stop for two months to control the weed and the dense metre-thick mats have been reduced to thin layers of smelly, rotting material. However, it is already shooting again, and follow-up spraying will be needed.

Alligator weed can be carried by stock, boats or farming equipment. The weed in Barren Box Swamp may have been brought in by recreational boat users from the Sydney or Newcastle region.

The swamp's water is distributed for stock and domestic use on surrounding grazing properties.

The task force was formed to co-ordinate the eradication program by NSW Agriculture, the departments of Fisheries and Water Resources, the Environment Protection Authority, the National Parks and Wildlife Service, and local government.

"The control program at this stage has been very effective," said Mr McIntosh.

"However, the major concern at the moment (is) preventing the weed entering the land-based form around the shores of the swamp and secondly controlling a new outbreak in the Mirrool Creek Floodway."

When alligator weed becomes land- rather than water-based, it puts down an extensive root system and is even more difficult to control. It destroys normally productive pasture.

Mr McIntosh said that unless the weed was controlled it posed a major threat to the aquatic habitat across the Hay plain and in the lower Murrumbidgee and Lachlan valley.

"It has the potential to destroy sensitive wetland environments," he said. "It stifles our native plants and fishes in those wetland environments. Very little can survive with alligator weed once it gets a firm hold."

He said the task force would have a fair idea of its success by December when spring and summer regrowth could be assessed. However, it would take two years to confirm whether the weed had been eradicated.