Fact Sheet Drought Contingency Measures The 12 month period ending March 2007 is the driest 12 month period for the River Murray in 115 years of historical inflow records. A repeat of the same rainfall pattern for another 12 months would result in even lower inflows due largely to reduced inflow from groundwater systems and a smaller volume of water transferred to the River Murray from the Snowy Mountains Scheme. While rainfall in the first three months of this year was near average over much of the Murray catchment, there has been little improvement in run-off. It will take significant and sustained rainfall to yield enough run-off to replenish major water storages. It is likely to take several years of well above average rainfall before storages return to long term average levels. If record low inflows continue, contingency measures will be needed to ensure that there is enough water to meet critical needs of all the towns and cities that rely on the Murray from Albury to Adelaide , as well as critical domestic and stock requirements. Under that extreme scenario, there would be no water available for irrigation or the environment. Although the probability of this extreme scenario eventuating is very low, it is nevertheless important that contingency planning continues until such time that there is sufficient rain and inflow. In an extreme dry inflow scenario under which there is only sufficient water to meet critical human needs, managing evaporation will be critical. In this situation, evaporation will be about three times as much as the volume of water needed for critical human needs. Accordingly, contingency measures to increase water availability must focus on reducing evaporation. Contingency plans currently underway Temporarily disconnecting wetlands A group of wetlands in South Australia and NSW have been identified as providing opportunities to save relatively large volumes of water by minimising evaporation, with manageable costs and impacts. State governments and the Murray-Darling Basin Commission are identifying triggers to guide the closure and reopening of wetlands. Disconnecting wetlands involves placing a temporary barrier between the River and the wetland. There are eight wetlands in NSW being investigated, which could yield a saving of about 40 GL. In South Australia , 27 managed wetlands closed their regulators during 2006, contrary to their management plans, to reduce evaporative losses by approximately 15 gigalitres. These wetlands remain closed and are now at risk of deteriorating ecologically. Investigations and community consultation is underway regarding the closure of nine unregulated wetlands, including Lake Bonney , which could yield additional savings of 42 GL. A number of other wetlands will be considered in subsequent investigations. In Victoria , there are a large number of wetlands such as the Kerang Lakes , Lake Boga and Kow Swamp that are supplied via irrigation systems and would be disconnected during times when irrigation allocations are low and there is insufficient water available to meet evaporative losses in the channel system. Wetlands in the River Murray and the native plants and animals that live in them are adapted to periodic wetting and drying. Re-introducing wetting and drying cycles can have positive environmental outcomes. However, after long periods of flooding, some wetlands may become acidified or salinised if they are then disconnected and dried out. Therefore, while disconnecting wetlands my deliver long-term environmental benefits, environmental managers need to strike a balance and avoid drying out those wetlands where damage may occur. Urban water restrictions It will be important to introduce consistent urban water restrictions to all areas reliant on water from the River Murray. Restriction regimes vary from state to state, and even within states. However, if there is no improvement in water availability, each state is likely to introduce urban restrictions equivalent to no outside water use on or before 1 July 2007 . Pumping of water to Mt Lofty Storages in South Australia A pumping schedule has been developed to ensure an additional 60 GL of water from the River Murray is pumped into storages in the Mount Lofty Ranges for Adelaide before the end of June 2007. In addition, Adelaide water supply system pumps on the Murray will be lowered during 2007 to allow pumping to continue even if Lower Lakes fall well below historic minimum levels, and hence maintain a water supply for Adelaide . Lowering end-of-season reserve target in Lake Victoria Water levels at the Lake Victoria storage will be lowered at the end of the irrigation season. Water that would normally need to be transferred to Lake Victoria will instead remain in deeper storages upstream to minimise evaporation. Reducing minimum flow targets At the end of an irrigation season, it is normal practice to reduce river flows to ‘minimum flow targets’ unless unregulated inflows exceed minimum rates. This year flows have been reduced earlier than usual. Operating at these lower levels aims to conserve water upstream. It will increase flexibility and reduce evaporation losses by retaining as much volume as possible in Hume and Dartmouth Reservoirs. Possible future measures Temporary weir at Wellington In the event that extreme low flows to South Australia persist long enough for the pool level below Lock 1 to fall below the level at which major SA Water pumping stations can operate, a temporary weir at Wellington could be built to help maintain a pumping pool and ensure that urban water can still be supplied. A feasible site has been located across the neck of Lake Alexandrina , between Willow Point and Pomanda Island . A decision to construct the weir will be made by the South Australian Government in June 2007. Snowy Scheme releases Water from the Snowy Scheme has been a vital source of water for both the Murray and Murrumbidgee Rivers , particularly during drought. Water available from the Scheme is also at a record low level. Consideration is being given to the role of the Snowy Hydro in 2007–08 in terms of securing a more favourable release pattern from the Snowy Scheme to assist in meeting critical downstream water supply needs. Under flexibility arrangements agreed in 2005, Snowy Hydro has already transferred about 200 GL to the River Murray, which it was not obliged to supply until 2007–08. Much of the water has been used to meet late season demand. This has allowed an equivalent volume to be stored in Dartmouth Dam, which experiences the lowest level of evaporation. Extraordinary weir drawdowns Weir pool levels in NSW and Victoria may be drawn down slowly from autumn through winter of 2007 to sustain minimum flows in the mid reaches of the River Murray, should tributary inflows remain very low. Weir pools most likely to be impacted are Lake Mulwala (Yarrawonga Weir), Torrumbarry Weir and Stevens Weir (on the Edward River ). Lock 8 and potentially Locks 9, 10, 11 and 15 could also be drawn upon if required. In South Australia , weir pools will be kept as close to full supply level as possible. Keeping weir pools in South Australia almost full prevents increases in saline groundwater inflows and thus helps contain salinity during low flow periods. With flows to South Australia being reduced to about 1300 ML/day in April, there is a possibility that any periods of warmer weather could result in evaporation and consumption exceeding inflow, in which case weir pools would temporarily fall slightly. Other investigations South Australia is continuing to pursue other options for supplying water and reducing pressure on the River Murray, including recycling and desalination. However, these options are longer-term prospects rather than solutions to the current water supply situation. How do I get more information? The Murray-Darling Basin Commission publishes regular drought updates, and will release periodic operational outlooks over the remainder of this season and next. This information is available at www.mdbc.gov.au and from the Australian Government and relevant State Government Agencies. Or contact the MDBC information officer at http://www.mdba.gov.au/contact May 2007 .