Page 412 - Week 02 - Tuesday, 15 February 2005
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As we all know, water is fundamental to the prosperity of the ACT and the surrounding region. This government is the first ACT government to prepare and implement a comprehensive policy which we have called “Think water, act water” which will ensure the community has access to a secure supply of high-quality water into the future.
Native vegetation is certainly an important component in the management of catchments and in ensuring water quality. It is not, however, the only issue to be taken into account, as we have clearly set out in the August 2003 report Shaping our territory: options and opportunities for non-urban ACT. Catchment management for its own sake and for water quality utilises a range of vegetation. Professional catchment management is about how we assess the needs of the catchment and then utilise various tools, including native vegetation, to achieve the outcomes we are seeking on a sustainable basis.
The government is working towards a hierarchy of outcomes from our water catchments in order of priority. We are seeking security of water supply, protection of water quality, protection of the environment, provision for recreational use, and provision of commercial use in forestry and farming. The 2003 bushfire affected us in ways beyond which most of us fully understand. It was a catastrophic event causing land disturbances not seen in the area for several hundred years. There is no quick answer or quick fix. Our water supply catchments were almost burnt out. The Cotter, indeed, was completely burnt. The result is that the amount and quality of water being delivered to the catchments has changed.
The water restrictions that we continue to face in Canberra are due in some part to catchment damage. The Cotter catchment is our most important source of water. It was subject to catastrophic degradation following the January 2003 fires. It can, of course, be considered as a catchment in two parts. The area surrounding Corin and Bendora dams is one part and the lower Cotter surrounding the Cotter Dam is the second part. The difference between the two parts of this particular catchment relates to land use based on topography and vegetation.
Corin and Bendora dams are each surrounded by the Namadgi National Park where native vegetation is the basis for the catchment, that is, the eucalypt forest, the bogs and the riparian zones which provide a set of ecosystem services, including water filtration, erosion protection, water storage and nutrient retention. That regrowth will see water filtration restored through intact canopy and ground cover so that water falling on the landscape and passing through the landscape is filtered, removing particles and nutrients. The result will be that very clean water again runs off that landscape. It was, of course, because of that particular natural filtration system that for so many years the ACT has managed to provide the average daily needs of the people of Canberra without a water treatment system being required
The regrowth will provide natural erosion protection because the vegetation binds the soil, creates mass in the soil to facilitate water absorption and forms small barriers to catch water and soil movement to allow it to settle before building speed through the gullies and down the streams. Clearing of vegetation by catastrophic natural events, for instance, fires, does expose, of course, the soil to erosion. Native vegetation also facilitates water storage. Intact swamps and bogs act as massive natural sponges, slowly releasing water to maintain streams. In the upper reaches of the Cotter the broad
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