Health report for northern Victoria’s rivers
“The harvesting of water from rivers and aquifers, altered flow regimes, loss of habitat connectivity and water pollution are key pressures on the environment arising from the State’s water management. Drought and climate change compound these pressures.” (6)
The Sustainable Rivers Audit (7) report on the ecological health of Murray-Darling Basin rivers paints a damning picture of northern Victoria’s rivers. All are rated as being in poor or very poor health, with the Goulburn in the worst condition of all the 23 rivers of the Basin. None are rated as being in good condition on any measure (except the Ovens and the Kiewa for hydrology) and the Campaspe and the Goulburn share the dubious distinction of having the lowest fish health scores for the Basin. This means that most of the expected native fish are missing or present only in low numbers or as under-sized individuals, and that fish populations are heavily dominated by introduced species like carp and trout. Invertebrate scores show that most of the disturbance sensitive species like stonefly and mayfly larvae are missing across much of northern Victoria. As invertebrates occupy an essential position near the base of the food chain, their absence has serious knock-on effects.
These poor scores are not the result of the current extended period of low inflows. Rather they are the end result of many years of well documented decline in river health driven by extraction and storage of water for agriculture, and the resultant changes in flow regimes. In the words of Dr Paul Humphries, it is as if ‘our rivers – and the animals and plants that live in them - have been exposed to massive climate change for more than 100 years.’ (8)
These problems have been documented in a steadily growing number of studies and reports, such as the Index of Stream Condition and the Victorian State of the Environment Report 2008. Basin states have attempted to rectify them through initiatives such as the Murray-Darling Basin Cap and the Living Murray program, and state based policies such as the Victorian River Health Strategy. However the Sustainable Rivers Audit shows that these measures have not succeeded in halting the long decline, which is only being accelerated by unprecedented low inflows driven by drought and climate change.
References
(6) Dr Ian McPhail, Victorian Commissioner for Environmental Sustainability, 4 December 2008
(7) Davies PE, JH Harris, TJ Hillman and KF Walker 2008. SRA Report 1: A Report on the Ecological Health of Rivers in the Murray–Darling Basin, 2004–2007. Prepared by the Independent Sustainable Rivers Audit Group for the Murray – Darling Basin Ministerial Council.
(8) Humphries, P (2008) The drought we had to have? Science Alert opinion, http://www.sciencealert.com.au/opinions/20081508-17809.html viewed 25/8/09
