Amendment date: 30 August 2017 1. Title of the measure Improved flow management works at the Murrumbidgee Rivers – Yanco Creek off-take 2. Proponent undertaking the measure NSW 3. Type of measure Supply 4. Requirements for notification a) The measure will be in operation by 30 June Yes 2024 b) The measure is not an ‘anticipated measure’ Yes ‘Anticipated measure’ is defined in section 7.02 of the It is a new measure (not already included in the Basin Plan to mean ‘a measure that is part of the benchmark conditions). benchmark conditions of development’. c) NSW agrees with the notification Yes 5. Surface water SDL resource units affected by the measure This measure identifies all surface water resource units in the Southern Basin region as affected units for the purposes of notifying supply measures. The identification of affected units does not constitute an agreement between jurisdictions on apportioning the supply contribution, which will be required in coming months. 6. Details of relevant constraint measures The Murrumbidgee constraints management strategy (see separate supply measure notification) will improve the ability to release water from storages to create higher flows along the Murrumbidgee River. The improved flow management works set out in the Improved flow management works at the Murrumbidgee Rivers – Yanco Creek off-take measure, will further improve the environmental outcomes for the mid- Murrumbidgee wetlands. 7. Date on which the measure will enter into operation The date by which the measure will enter into operation is 30 June 2024. 8. Details of the measure a) Description of the works or measures that The proposed works include: constitute this measure a) Yanco Creek Regulator and Fishway – a new regulator to be installed in Yanco Creek to allow regulation of flows between the Murrumbidgee River and Yanco Creek. Operation of the regulator during targeted environmental watering events for the mid-Murrumbidgee improves watering efficiency of the environmental assets. b) Increased weir pool level at Yanco weir – the weir pool will be raised at Yanco weir so that environmental flows can be provided to Yanco Creek without having to provide large flows downstream in the Murrumbidgee River. c) New Murrumbidgee Regulator at Yanco Weir – an investigation of the structural and mechanical capacity of the existing gated regulator at Yanco weir indicates that it is not suitable for upgrading for the increased water level associated with the new weir pool design level. It is proposed to install a new regulator in the meander reach that currently has the older Yanco fixed crest weir. d) Fishway at new Murrumbidgee Regulator - the project will provide for both upstream and downstream fish passage in the Murrumbidgee River at Yanco weir. 1 The location of proposed works are described and shown Section 3.2 in Attachment A. b) Capacity of the measure to operate as a Yes supply measure ‘Supply measure’ is defined in section 7.03 of the Basin Plan to mean ‘a measure that operates to increase the quantity of water available to be taken in a set of surface water SDL resource units compared with the quantity available under the benchmark conditions of development’. c) Geographical location of the measure The site of the proposed works is at the Yanco Creek off-take from the Murrumbidgee River, approximately 20km to the west of the town of Narrandera. The new Yanco Regulator and Fishway will be on the Yanco Creek. The new regulator and fishway on the Murrumbidgee River will be near the site of the original (1928) Yanco Weir, downstream of the Yanco Creek off-take. See section 2.1 and figures 1 and 2 in Attachment A. d) Spatial data describing the inundation The extent of additional wetland inundation along the extent associated with the operation of Murrumbidgee River during targeted higher flow events will the measure be assessed by the MDBA as part of the combined modelling of supply measures. The increased weir pool height proposed at Yanco Weir will lead to higher water levels in the upstream river reach towards Narrandera. This extent has been modelled, and is described in Figures 23 and 24 in Attachment A and Appendix C in Attachment D. e) Representation of the measure in the An adjusted benchmark model for the Murrumbidgee was MDBA modelling framework developed by NSW DPI Water in consultation with the MDBA. All NSW Murrumbidgee projects were then incorporated into the adjusted benchmark model (See Section 2.3 of Attachment C, this measure is referred to in Attachment C as the “Yanco off-take”). The measure is further represented in the updated benchmark model, as detailed in Attachment E. Modelling of the measure by the MDBA will be on this work, with changes to how the measure is represented in the framework detailed in Attachment D. f) Representation of each operating strategy Modelling of this measure, which is described at Attachment in the MDBA modelling framework. B, is based on the operation of the regulators described in Section 3.2 of Attachment A, and Attachment F. 2 Attachments: A NSW DPI Water, November Business Case: Improved flow management works at the Murrumbidgee 2015 Rivers –Yanco Creek offtake B DHI, March 2016 Murrumbidgee SDLA – Project models C Alluvium (2013), Yanco Creek system environmental flow study (final report), report prepared D MDBA, 2017 No tification amendmen t 1 – Mu rrum bidg ee prop osals E DPI, April 2017 Technical notes on Updating the Murrumbidgee SDLA Benchmark Model 2017 F DHI, February 2017, Revised Yanco Creek and Effluent Creek operating strategy representation for memorandum modelling 3 Improved Flow Management Works at the Murrumbidgee River - Yanco Creek Offtake ‒ Business Case Executive Summary Introduction The ‘Improved flow management works at the Murrumbidgee Rivers – Yanco Creek offtake’ Project (the Project) will achieve SDL Adjustment through improved delivery of environmental flows to the Mid Murrumbidgee wetlands. Complementary works will also improve fish passage for large bodied fish along the Murrumbidgee River and regulate flows to the Yanco Creek to deliver improved flow regimes. Contribution to SDL adjustments Yanco offtake was constructed to develop and expand agricultural production in the Yanco system. The offtake joins Yanco Creek to the Murrumbidgee River and provides flow to the creek system, even when flow in the Murrumbidgee River is quite low. The current infrastructure arrangement includes an existing gated regulator on the Murrumbidgee River (Yanco Regulator) and an existing (older) fixed crest weir (Yanco Weir). The Yanco Regulator is designed to divert flows into Yanco Creek, in combination with the water level created by Yanco Weir which determines the flow that Yanco Creek receives. Under current operation approximately 10% of flow from the Murrumbidgee River is diverted into the Yanco Creek system through the Yanco offtake. The proposed works and measures have been designed to increase the proportion of higher flows that reach the mid- Murrumbidgee and lower Murrumbidgee wetlands downstream of Yanco Weir. The proposed structures also allow targeted diversion of water into the Yanco system to reinstate a more appropriate regime of freshes, bank-full and overbank flows recommended by the Yanco Creek System environmental flows study. The volume of water required to be reinstated in the Yanco system is smaller than the flows added to the Murrumbidgee by the proposed structures, leading to an improved environmental outcome along the Murrumbidgee River. The proposed works include: • Yanco Creek Regulator and Fishway – a new regulator to be installed in Yanco Creek to allow regulation of flows between the Murrumbidgee River and Yanco Creek. Operation of the regulator during targeted environmental watering events for the Mid Murrumbidgee improves watering efficiency of the environmental asset. • Increased weir pool level at Yanco weir - The weir pool will be raised at the Yanco weir so that environmental flows can be provided to Yanco Creek without having to provide large flows downstream in the Murrumbidgee River. • New Murrumbidgee Regulator at Yanco Weir - An investigation of the structural and mechanical capacity of the existing gated regulator at Yanco weir indicates that it is not suitable for upgrading for the increased water level associated with the new weir pool design level. It is proposed to install a new regulator in the meander reach that currently has the older Yanco fixed crest weir. • Fishway at new Murrumbidgee Regulator - The project will provide for both upstream and downstream fish passage in the Murrumbidgee River at Yanco weir. The existing ii NSW DPI Water, August 2015 Improved Flow Management Works at the Murrumbidgee River - Yanco Creek Offtake ‒ Business Case structures are significant barriers to fish migration in both directions, except during high flow events. Anticipated environmental benefits The Mid Murrumbidgee wetlands comprise relatively intact flood-dependent vegetation communities that provide crucial habitat for numerous conservationally significant fauna species, and are targeted for inundation through several of the Specific Flow Indicators set by the MDBA. The wetlands are an important area for waterbirds including breeding of colonial nesting waterbirds and contain a range of riparian and wetland vegetation communities that are critical to several fish species in the Murrumbidgee, including Murray Cod. Anticipated environmental benefits associated with the project stem from the ability to achieve targeted