The Nature Conservation Society of SA has a number of key concerns with the Draft Environmental Impact Statement for the proposed temporary weir near Pomanda Island. These involve matters of National Environmental Significance, the ongoing management of the Site as a Ramsar wetland, and the lack of accurate information on the period for which the weir will be operational.
Issue: Lack of Assessment of full impacts of weir on Matters of National Environmental Significance (MNES)
The trigger for weir construction (water level in Lake Alexandrina at -1.5mAHD) is identified because it is the point at which unmitigated acidification of Lake Alexandrina is predicted to occur. However, the construction and operation of the weir will result in the level of the Lake dropping to -2.1mAHD. Although weir construction is presented as a solution to declining water levels it will have the perverse outcome of accelerating water level reduction and exacerbating the potential problems. This in turn will increase the need for remedial action to avoid acidification (eg flooding the Lake with seawater). The EIS does not address these remedial actions and their effects on the environment but needs to, as they are a direct consequence of weir construction and operation. Weir construction is directly linked to many more potential impacts on MNES than have been dealt with in this EIS.
Solution: The EIS should examine the impacts of actions to increase water levels in the Lake, as these are a direct consequence of weir construction and operation.
If the water level at -1.5mAHD compromises water quality in the Lake to the extent that it threatens the quality of drinking water upstream, then surely this must also pose a severe risk for species dependent on the Lake and its water. Accelerated decrease in water levels in the Lake as a result of the weir and the resulting acceleration in salinity and acidification risk will intensify threats to these species even further, and compromise the values for which the Lakes are RAMSAR listed. This has not been identified as a consequence of weir construction (eg Table 16-1) and is not addressed by the EIS.
Solution: The EIS should examine the impacts of accelerated increase in salinity and acidity of water within the Lake on MNES as these are a direct consequence of weir construction and operation.
Issue: There are shortcomings in the Environmental Assessment, with regard to key habitats and species that characterise the Lakes as RAMSAR wetlands
The Convention on Wetlands, signed in Ramsar, Iran in 1971 (more commonly known as the Ramsar Convention) is an intergovernmental treaty dedicated to the conservation and “wise use” of wetlands. The Convention’s mission is: ‘the conservation and wise use of wetlands by national action and international cooperation as a means to achieving sustainable development throughout the world’.
The Convention encourages the designation of sites containing representative, rare or unique wetland types, or that are important for conserving biological diversity to the List of Wetlands of International Importance (RAMSAR sites). These sites need to be managed to ensure their special ecological values are maintained or improved.
Either through the construction phase or through changing river water levels, water quality and flow cycles, the weir development has a high risk of destroying or seriously degrading the RAMSAR Wetland communities of the lower River Murray Lakes. These littoral wetland communities include Phragmites australis and Bullrush Reedbeds which, near the proposed weir site, contain several rare and declining plant species, including: Senecio longicollaris (Nominated as Vulnerable under the EPBC Act 1999); Shrubby Groundsel (Senecio cunninghamii var. cunninghamii), a species “still extant along the River Murray but extinct for the Yorke Peninsula & Southern Lofty botanic regions and considered to be Vulnerable in SA,” (Bates 2008); and Purple Loosestrife (Lythrum salicaria) - Rare for South Australia DEH (2008).
Solution: The EIS needs to examine the full range of flora and fauna species, including state listed and locally threatened species, as these form part of the ecological values which characterise the Lakes as RAMSAR wetlands.
Issue: Lack of accurate information on period of operation
The proposed timeframe for weir removal is three years. As noted by Muller 2009 (page 4) “Of greatest concern to the process of assessing the risks associated with the proposed weir is the lack of predictions on when the removal triggers will be met and hence on when the removal of the proposed weir will commence” and that “impacts are more strongly adverse as deployment time increases”. Muller also states that “because of uncertainties around the timing of construction and period of operation, an update of this risk assessment will be needed to assess the risks more thoroughly and inform a robust environmental management plan, if the weir were to be built.” This implies that the risk assessment within the current EIS is inadequate for a weir which will remain in operation for the medium to long term.
Solution: the EIS should assume the weir to be a permanent structure. This would also allow for discussion and development of environmental safeguards and mitigation to lessen the impacts of Matters of National Environmental Significance in the context of a permanent weir structure.
General Editorial comments:
7.3 Bool and Hacks Lagoons are not upstream of this weir as is implied in the text
7.5.6 “Plant associations in close proximity to the weir” only one of the 11 dot points is actually a plant association
Bates, R.J (2008) South Australian Senecio. Unpublished report. Threatened Plant Action Group, Adelaide.
DEH (2007) Australia's Ramsar Sites. Department of the Environment and Heritage, http://www.environment.gov.au/water/publications/environmental/wetlands/pubs/ramsar.pdf
DEH(2008) Schedule 9—Rare species of the National Parks and Wildlife Act 1972—21.2.2008 Update. http://www.legislation.sa.gov.au/LZ/C/A/NATIONAL%20PARKS%20AND%20WILDLIFE%20ACT%201972/CURRENT/1972.56.UN.PDF#page=92
Muller K.L. (2009) An Assessment of Ecological Risks to Matters of National Environmental Significance for the proposed weir at Pomanda Island, near Wellington, S.A. Prepared for South Australian Department for Environment and Heritage, February 2009.