A simple analysis suggests that, if constructed, the proposed dam at Traveston Crossing will replace approximately 76 square kilometres of prime irrigated farmland and the community it supports with a tepid shallow swamp prone to algal blooms, weed infestation and the health risks of mosquito-born disease (like Ross River and Dengue Fever). Surface evaporation alone would result in the annual loss of a volume of water equivalent to at least half the capacity of Borumba Dam. Although the dam is expected to hold approximately 660 billion litres when full (more than 14 Borumbas), it would depend on the flood events for which the Mary is famous to fill it. The rest of the time it will more likely be a vast plain of receding shallow mudflats and weedy swamp, not the sparkling clean water-sports paradise that some might imagine. Its ability to provide regular supply and maintain environmental flow in periods of sustained low flow like the last 6 years is open to question. In spite of this, the ability of such a dam to withstand or significantly mitigate very extreme floods like the 1999 and 1974 floods is also open to question, as is its ability to maintain storage capacity against sediment build up.
We ask the State Government to present some firm science and engineering analyses to the public to justify it's decision to dam the Mary River. |
