Grading sheep on a property near Forbes, New South Wales Summary of LACHLAN REGION From the Guide to the proposed Basin Plan This publication summarises proposals outlined in the Guide to the 0 65 1proposed30 km Basin Plan as they relate to the Lachlan region. THE REGION The Lachlan region is based around the Lachlan River in central western New South Wales. The Lachlan River flows west from its headwaters in the foothills near Breadalbane between Yass and Goulburn, and terminates in the Great Cumbung Swamp near Oxley in south-west New South Wales. Its topography varies from tablelands in the east, through sloping country in its central region, to plains in the west. Water USE AND ENVironMental health lucerne) and domestic and stock demands. The Authority has compiled the current limits There are also non-consumptive water users for all forms of water extraction in the Murray– such as recreational and cultural users. Darling Basin. For surface water these current In the Lachlan region, there are a number of diversion limits include watercourse diversions factors indicating poor ecological condition. For for town and community water supplies, example, the Lachlan Valley fish community irrigation and industries, floodplain harvesting, is in extremely poor condition. There is a low and interception activities such as farm dams diversity of native species and fish biomass is and forestry plantations. For groundwater they mainly made up of alien species. Vegetation include all water diverted from the aquifers condition is moderate with some 50% of of the area. Current diversions are limited by remnant vegetation cover in the catchment. existing transitional and interim water resource Hydrological conditions in the Lachlan are plans where these are in place. These are considered moderate to good while stream existing plans, prepared by Basin states, and condition is extensively modified and impaired. recognised under the Water Act 2007 (Cwlth). Overall, macroinvertebrate diversity is Where there are no existing plans, or plans do moderate. The major surface water quality not apply to certain types of water extraction, issues in the Lachlan are increasing salinity, the current diversion limit reflects the current high nutrient levels, increasing frequency of level of use. algal blooms, high turbidity, pesticides and The surface water long-term average current thermal pollution. diversion limit for the Basin as a whole has been estimated at around 13,700 GL/y and at ASSESSING ENVironMental Water NEEDS 618 GL/y for the Lachlan region. The Basin Many of the environmental assets and wide groundwater long-term average current functions of the Murray–Darling Basin have diversion limit is 1,786 GL/y. been degraded by the over-extraction of water from the Basin’s rivers. The Act and Basin Lachlan region surface water Plan seek to address the over-extraction of current diversion limit (GL/y) water to restore and maintain the Basin’s Interceptions Watercourse diversions Total key environmental assets and key ecosystem 316 302 618 functions. To determine sustainable diversion limit (SDL) There are many different water users in the proposals it is necessary to work out how much Lachlan, including those that divert water to water is needed to sustain the health of the supply towns, industry (including significant Basin’s river systems, wetlands and floodplains. mining operations in the Orange Basalts), To do this, the Authority has undertaken irrigation (including cotton, winter and summer an assessment of the environmental water pasture, hay and cereal grain production and requirements of key environmental assets and key ecosystem functions across the Murray– Darling Basin. In the most part, the assets assessed are large flood-dependent wetland and floodplain systems that support populations of waterbirds and fish, and large forests and woodlands. The assessment of key ecosystem functions gave particular attention to the environmental water requirements of rivers, and system wide processes such as connectivity between rivers and floodplains. Together, these assessments included specific analysis of flows at 106 hydrologic indicator Canola crop near Cowra, New South Wales sites across the Basin (88 sites to assess the water needs for the Basin’s key ecosystem to account for the effect of climate change functions and 18 to assess the water needs for on surface water SDL proposals. The SDL key environmental assets), as well as analysis proposals for groundwater do not include a of end of system flows in each region. climate change component. The environmental water requirements at a The SDL proposals would require a reduction Basin scale have been estimated between in the current long-term average surface water 22,100 GL/y and 26,700 GL/y (an increase diversion limit at the Basin scale from 13,700 between 3,000GL/y to 7,600GL/y from the 19,100 GL per year to between 10,700 GL and 9,700 GL GL/y currently available for the environment). per year (reduction between 3,000 GL and 4,000 In the Lachlan region, 58 key environmental GL per year or 22% to 29%). assets have been identified. Of the 106 For the Lachlan region this would equate to hydrological indicator sites across the Basin the reduction in the current long-term average Lachlan region contains 5 hydrological indicator surface water diversion limit from 618 GL/y to sites for key ecosystem functions and 3 between 574 GL and 549 GL per year (reduction hydrologic indicator sites for key environmental between 44 GL and 69 GL per year or 7% assets. These are listed below: to 11%). • Great Cumbung Swamp The SDL proposals would also require a • Booligal wetlands reduction in the current long-term average groundwater diversion limit at the Basin scale • Lachlan Swamp by an aggregate 186 GL or an average reduction The environmental water requirements for the of 10% across the Basin. The reductions in Lachlan region have been estimated between current diversion limits are required in only 11 1,181 GL/y and 1,295 GL/y (an increase between of the 78 groundwater SDL areas. No reductions 44 GL/y and 158 GL/y from the 1,137 GL/y are proposed for the remaining 67 groundwater currently available for the environment) SDL areas where the current diversions are assessed as sustainable. Further information on assessing the environmental water requirements of the Basin SDL proposals for the surface water and is available at www.mdba.gov.au/basin_plan/ groundwater SDL areas of the Lachlan region water-assessment-report. are set out on page 5. SUStainaBLE DIVERSION LIMIT ProPOSALS SUPPorting coMMUNITIES at THE BaSIN AND REGIONAL Scale The Murray–Darling Basin Authority The Authority is required to establish new acknowledges that implementing SDLs long-term average SDLs for surface water may have significant social and economic and groundwater. SDLs represent the long- implications for individual entitlement holders term average amount of water which can be and communities across the Basin. used for consumptive purposes after meeting However, the Australian Government has the environmental water needs that have committed to recovering sufficient water access been identified. entitlements to fully offset the impact of SDLs In the Guide, the Authority presents the SDLs across the Basin, including the Lachlan region. as a range of scenarios for discussion at this This will be achieved through a combination stage, rather than choosing a particular value in of purchasing entitlements in the market this range. This range takes into account all the and investments in more efficient irrigation available evidence, the quality of that evidence, infrastructure. and the inherent uncertainty of modelling. Consequently, should these targets be met, The Authority has determined that 3% of the there are likely to be no reductions in individual current diversion limit (around 410 GL/y for the water entitlement holder allocations. Basin as a whole and around 19 GL/y for the For further information about these activities go Lachlan region) is an appropriate allowance to www.environment.gov.au/water. 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