Water Week

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Science has established how much water forestry uses, so that use should be part of South Australia’s water allocation policy says MHA

Posted by waterweek on 28 September 2007

Despite some robust debates at times, the Select Committee conducting hearings into the Penola Pulp Mill Authorisation Bill 2007 had come up with a unanimous view about what should be done with the bill, Independent MHA Kris Hanna said in the South Australian House of Assembly on 11 September 2007.

History important: Hanna said: “In essence, we are suggesting that the bill should proceed, but it should be heavily amended in its passage through parliament. One of the complications is that there is a great deal of history to the forestry plantations in the South-East and the allocation of water in the South-East. At first glance, it might appear that the bill had nothing to do with that history, but it soon became apparent to me that it was extremely important to go into the history of how water allocations are granted in the South-East and how forestry became as prominent as it is.”

Forestry affects water allocation: Hanna quoted extensively from a letter written by David Geddes, the Presiding Member of the South-East Natural Resources Management Board, to a local newspaper, which stated: “In the one million hectares of the lower SE, there is currently about 140,000ha of plantation forestry, of which 40,000ha is bluegum. Plantation forestry is recognised by the National Water Commission and others as a water affecting activity through interception of recharge to the aquifer and in some cases by direct extraction where shallow water tables exist. Not accounting for the impacts on groundwater will result in water resources being overallocated. The most recent assessment of the water resources shows that areas within the Lower South-East are approaching full allocation and in some instances are already overallocated. A number of areas are showing persistent signs of water level decline or salinity increase…”

Expansion planned: Allowing further unregulated demands on the water resource would damage the water resource and the environment, Geddes argued. The letter continued: “In June 2004, under a Regulation, the government set aside sufficient water budget to account for the recharge interception effects of 59,416ha plantation expansion. There is significant scope for plantation forest expansion on both sides of the state border, both in terms of land area and water resources. Over the last 18 months, there has been significant discussion with all water users, including plantation forest owners. As a consequence of those discussions, it is the board’s policy position that plantation forests be issued a water allocation for recharge interception, and where applicable, for direct groundwater extraction. The board has further resolved that where a management area is overallocated, and reductions are necessary, there would be no requirement for premature clearfelling.”

Two impacts of forestry on water resource: Hanna said that the forest industry had two impacts upon the water resource – by which he meant the two aquifers – one closer to the surface, much of it less than six metres from the surface, and the other deeper underground. One impact was simply that it stopped rain getting to the ground and therefore seeping into the underground aquifer. We therefore refer to that as the recharge interception. The second was that the trees suck up water where the water is less than six metres from the surface through the trees’ root system.”

Forestry water use now scientifically quantified: Hanna continued: “When policy was developed with the agreement of all stakeholders — some reluctantly, about five years ago — a document entitled the `Forest threshold expansion policy’ was created. As the member for Ashford mentioned, the committee did not actually end up getting a copy of that policy despite a request to the relevant government department. Essentially, the policy allowed for expansion of forestry in the South-East and a certain amount of recharge interception. In other words, it was quite okay for additional trees to be planted and for the impact in terms of recharge interception, but there was a limit to the amount that could be planted without purchasing additional water. Since that time, the extent of water taken through direct extraction by forestry plantation has become better understood. The figure that is put about is 2 megalitres per year per hectare… The fact is that this should now be taken into account in the water allocation policy for the South-East, and that is exactly what the South-East Natural Resources Management Board means to do. This is now out in the open as part of the consultation policy of the NRM board.”

Reference: Kris Hanna, Member for Mitchell, Political Party, Independent, House of Assembly, South Australia, 11 September 2007.

Erisk Net, 16/9/2007


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