Ord River Water Management Plan DECEMBER 2006 Water Resource Allocation and Planning Series Report no. WRAP 15 i Water Resource Allocation and Planning, no. WRAP 15 Ord River Water Management Plan Department of Water Level 4, 168 St Georges Terrace Perth Western Australia 6000 <www.water.wa.gov.au> Telephone +61-8-6364 7600 Facsimile +61-8-6364 7601 For more information about this report, contact Ian Loh, Program Manager. (08) 6364 6839 Recommended References The recommended reference for this publication is: Department of Water. 2006, Ord River Water Management Plan. Department of Water, Government of Western Australia, Water Resource Allocation Planning Series Report No WRAP 15. We welcome your feedback Feedback can be sent to us via the address above or through the Department of Water website www.water.wa.gov.au. December 2006 ISSN 1327-8428 (pbk). ISSN 1834-2620 (pdf). Subject of cover photograph Lake Argyle, Ord River Dam, Irrigation area and the Kununurra Dam. Department of Water Contents Contents .......................................................................................................................i Preface ........................................................................................................................v Summary .................................................................................................................... vi 1 Introduction..............................................................................................................1 1.1 Background......................................................................................................................1 1.2 Ord River water allocation planning .................................................................................2 1.3 Purpose of this plan .........................................................................................................6 1.4 Aims.................................................................................................................................6 1.5 Updating the plan.............................................................................................................7 1.6 Layout of document..........................................................................................................7 2 The lower Ord River ................................................................................................9 2.1 Ord River Basin..............................................................................................................10 2.2 Environmental attributes of the lower Ord River.............................................................10 2.3 The Ord River before regulation.....................................................................................12 2.4 The lower Ord River since regulation .............................................................................18 2.5 Ramsar wetlands and Cambridge Gulf ..........................................................................28 3 Ecological Water Requirements ............................................................................37 3.1 Definitions ......................................................................................................................37 3.2 EPA advice and revised management objective ............................................................37 3.3 Development of an interim EWR....................................................................................37 4 Environmental Water Provisions ...........................................................................43 4.1 Introduction ....................................................................................................................43 4.2 Social water values ........................................................................................................43 4.3 Native Title issues and the Ord Final Agreement...........................................................48 4.4 An interim EWP for the lower Ord River.........................................................................49 5 Commercial water demands..................................................................................53 5.1 Factors affecting irrigation demand................................................................................53 5.2 Stage 1 irrigation demands ............................................................................................53 5.3 Stage 2 irrigation demands ............................................................................................56 5.4 In-stream demands ........................................................................................................58 5.5 Other possible demands ................................................................................................64 5.6 Matching available water to expected demands ............................................................64 6 Establishing the water available ............................................................................65 6.1 Management objectives and allocation constraints........................................................65 6.2 Reservoir simulations.....................................................................................................66 6.3 Potential irrigation and electricity allocations..................................................................68 7 Water allocations and sustainable diversion limits ................................................77 7.1 In-stream allocations......................................................................................................77 7.2 Sustainable diversion limits from the Ord River .............................................................78 Department of Water i Ord River Water Management Plan Water Resource Allocation and Planning, no. WRAP 15 8 Implementing the plan - Managing use through water licensing............................83 8.1 Legislative basis for water licensing...............................................................................83 8.2 Licensing approach for the Ord River resource..............................................................83 8.3 Managing flows in the Ord River ....................................................................................84 8.4 Managing Stage 1 (current) water use...........................................................................86 8.5 Managing water use in M2 Supply Area.........................................................................90 9 The effects of additional allocations ......................................................................93 9.1 Changes to the flow regime of the lower Ord River........................................................93 9.2 Nutrient concentrations in the lower Ord River...............................................................97 9.3 The lower Ord geomorphology and ecology ................................................................ 102 9.4 Ramsar wetlands ......................................................................................................... 103 9.5 Changes in Cambridge Gulf......................................................................................... 106 9.6 Concluding remarks ..................................................................................................... 112 10 Reviewing and updating this plan........................................................................113 10.1 Updating the hydrology of the Ord catchment.............................................................. 113 10.2 Reviewing the current EWR and licensing the first phase of the M2 Supply Area ....... 113 10.3 Updating the current EWP and management plan....................................................... 113 Appendices..............................................................................................................117 References ..............................................................................................................179 Abbreviations...........................................................................................................184 Glossary ..................................................................................................................185 Contributors.............................................................................................................190 Where to from here?................................................................................................191 ii Department of Water Water Resource Allocation and Planning, no. WRAP 15 Ord River Water Management Plan List of Appendices Appendix 1 The Ord River Irrigation Project ........................................................................................119 Appendix 2 The 1999 Draft Interim Water Allocation Plan and EPA advice ........................................124 Appendix 3 Interim EWR and EWP flow regimes for the lower Ord River ...........................................129 Appendix 4 Community consultation ...................................................................................................147 Appendix 5 Irrigation demands ............................................................................................................168 Appendix 6 Water quality management of contaminants in drainage water ........................................176 List of Figures Figure 1: Location map showing key features of the Ord River Irrigation Project .....................................3