By Marina Carman
SYDNEY — A 25 km stretch of the Hawkesbury-Nepean river in Sydney's north-west is infested with a noxious weed, which is capable of killing fish and plant life, and even threatening human life.
The water hyacinth can double in size every five days and with a weight of 400 tonnes per hectare, any major movement could threaten bridges along the river. Build-up of the weed in narrow sections could cause flooding to areas not normally affected, create unsafe swimming areas and harbours for mosquitoes, which carry many serious diseases.
The Environmental Protection Authority has been aware of the situation since April last year, when it issued a licence to the local council to use herbicides in a bid to solve the problem. The EPA claims that the situation is "in control".
However, with seven Water Board sewage outfalls flowing into the river, the situation has worsened since April to the extent that it is likely to plague the river for up to 20 years.