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Prior to the major flood experienced across the Hunter in June 2007, the Wollombi Brook was up to 75% infested with the noxious aquatic weed Salvinia.
Salvinia is known to grow more rapidly through the warmer months, and with the higher temperatures experienced throughout November, the chances of the Wollombi area becoming re-infested this summer are high.
Salvinia molesta is an aquatic fern native to South America. It reproduces vegetatively and can double its mass within a few days. It can render dams and waterways unusable for livestock, irrigation, water birds, fish and other aquatic life, due to its ability to form thick, impenetrable multi-layered mats. For this reason it is considered to be one of Australia’s worst weeds and is recognised as a Weed of National Significance (WoNS).
Since 2005 the CMA has been working with Cessnock City Council, Hunter Councils, Conservation Volunteers Australia, the Land and Property Management Authority, and local Landcare groups, on a Salvinia control program in the Wollombi catchment to help landholders (who are legally obliged under the Noxious Weeds Act to control Salvinia on their properties) to get on top of the problem.
Salvinia tends to grow best in non- to low-flowing areas of water with high nutrient levels and warmer temperatures. Landholders can help by preventing nutrients from entering water bodies and retaining them in the soil where they are needed. Reducing the use of fertilisers and planting a buffer strip of native vegetation along the edges of waterways and dams are both great ways to do this.
While Salvinia has been significantly reduced in the Wollombi area, landholders need to be particularly vigilant at this time of year. The cost and time involved in removing the weed from infested areas can be dramatically reduced if it is caught in time.
Landholders in the Wollombi area are encouraged to keep a look out for the weed floating on dams or along the Wollombi Brook. If you suspect you have Salvinia on your dam or waterway, contact your local council weeds officer immediately for verification and advice.
