Managing water from Quick water facts How is water allocation decided? the The priority set by government is for secure and The Ord River is one of the Goomig farmland reliable water supplies to maximise the irrigation most significant waterways in potential of the region, while at the same time supporting hydro-electricity generation and sustaining . It provides for water Plain to an iconic agricultural project, a healthy downstream river environment. supports local tourism and The Department of Water is responsible for managing sustains a unique Kimberley Carlton Plain Tarrara Bar streamflow gauge Knox Creek and licensing water from the Ord River under the environment. Plain ^ Rights in Water and Irrigation Act 1914 (WA). Its We are seeing the largest Mantinea Green Swamp Ord surface water allocation plan supports the Knox Creek development of irrigated land government priorities through water allocation limits Ivanhoe Plain in the Ord River area since the Ord West which control the total volume of entitlements that can Bank 1960s. The Ord-East Kimberley be issued, and water release rules and water sharing

Eight Mile Creek Irrigation Expansion Project rules which are managed though licences. plans to increase the size of the Ord irrigation area by !( Kununurra The water release rules are particularly important Ð Lake Kununurra 15,400 hectares in the short Legend Kununurra Diversion Dam Ò during times of below-average storage and dry !( Towns term with potential for further ^ Streamflow gauge Packsaddle periods, and ensure the most effective water sharing. Plain expansion beyond this in ÒÐ Dam site The rules were set using a water balance model and into the Roads that weighs up hydrology, water demands, reliability, Rivers Northern Territory. M1 channel releases to meet the different needs, and operational M2 channel constraints. As irrigation expands, the water release The WA Government signed M2N supply channel Ord River Govt EOI 2011 rules will be adjusted slightly to maintain a an agreement with Kimberley Lakes 95 per cent reliability of supply for each phase of Agricultural Investment (KAI) Sorby Hills Mining Area for development of the Goomig Stage 1 areas irrigation development. Stage 2 areas (7,400 ha) and Knox Plain Goomig farmland Vegetation management area Ord River Dam (6,000 ha) expansion areas. ÒÐ Non irrigation areas An additional 2,000 ha will Land not available be developed within existing agricultural areas at the Ord West Bank, Packsaddle Plain and Ord East Bank. ± There is potential to develop a 0 10 20 further 9,000 ha in the medium Kilometres

Ord Ord term in the Carton Plain and Locality Map September 2013 surface water allocation plan surface water allocation plan Mantinea areas. Further information !( KUNUNURRA The Ord surface water allocation plan is available on our website Two additional areas totalling HALLS CREEK !( 5,000 ha known as Cockatoo www.water.wa.gov.au sands have been identified NT The Department of Water is assessing and advising government for possible development. Up WESTERN AUSTRALIA on water supply options should additional water be needed for to 14,000 ha of land has also SA irrigation expansion. If major infrastructure or supply system been identified for possible Lower Ord River Government of Western Australia Department of changes are agreed, then water management arrangements will development in the Northern Water Looking after all our water needs Water resource allocation Western Australia Western be updated accordingly. and planning report series Territory. Report no 48 Map reference: C2114/0004 September 2013 Department of Water 168 St Georges Terrace, , Western Australia PO Box K822 Perth Western Australia 6842 Phone: 08 6364 7600 Fax: 08 6364 7601 www.water.wa.gov.au Current and proposed irrigation development areas 96483 300 0913

HowHow the the system system works works WaterWater flows flows from from south south to tonorth north along along the the Ord OrdRiver River and and is isstored stored in inLake Lake Argyle Argyle by theby the Ord OrdRiver River Dam, Dam, andand Lake Lake Kununurra Kununurra by bythe the Kununurra Kununurra Diversion Diversion Dam. Dam. TheThe Department Department of Waterof Water licenses licenses the the Water Water Corporation Corporation to storeto store water water in thein the lakes lakes and and to operateto operate the the dams dams in in accordanceaccordance with with licence licence conditions. conditions. The The Ord Ord Irrigation Irrigation Cooperative Cooperative (OIC) (OIC) and and self-supply self-supply irrigators irrigators hold hold licences licences to taketo take water water from from the the Ord Ord River River downstream downstream of theof the Ord Ord River River Dam. Dam. 2014 SinceSince 1996 1996 a hydropower a hydropower plant plant has has operated operated on onthe the Ord Ord River River Dam. Dam. Water Water is releasedis released through through turbines turbines to generateto generate Looking after all our water needs.

electricityelectricity for forlocal local towns towns and and the the Argyle Argyle Diamond Diamond mine. mine. Water Water releases releases for forhydropower hydropower generation generation are are the the largest largest 9482 300 0414 releasesreleases from from Lake Lake Argyle. Argyle. Contact Information IrrigationIrrigation is theis the primary primary consumptive consumptive use use of waterof water from from Lake Lake Argyle. Argyle. The The other other main main water water benefit benefit is foris forthe the lower lower For more information, contact the Kununurra Regional Office on 08 9166 4116 OrdOrd River, River, below below the the Kununurra Kununurra Diversion Diversion Dam. Dam. Flows Flows in thein the lower lower part part of theof the river river come come from from Lake Lake Argyle Argyle and and the the or at 27 , Kununurra Western Australia 6743. DunhamDunham River, River, and and support support water water dependent dependent ecosystems ecosystems as aswell well as ascommunity community values. values. 2691-0414 Water releases for hydropower Boating and navigation Pacific Hydro Ltd own and operate the Ord River Dam Damming of the Ord River and all year-round releases Power Station under a water supply agreement with for power have significantly enhanced boating and the Water Corporation. The Department of Water sets navigation on the river, with both lakes and the lower power station release rules so that water released for Ord River now being popular boating and tourism power each month does not reduce the reliability of locations. water for irrigation in future years. Even when flows are in excess of minimum required Since operation began, most of the water released environmental flows or natural dry season levels, from the dam has been for hydropower. The volumes the need to store water for longer periods to reliably released have been sufficient to meet Stage 1 provide for increases in water allocations will affect irrigation demands, and are well in excess of the the ease of navigational access. needs of the lower Ord River environment. Boating on Lake Argyle will not be affected by As lake levels decline due to low inflows or high power increased demands but boating access on Lake demand, monthly hydropower releases need to be Kununurra, especially close to the Ord River Dam, reduced to maintain reliability of supply for irrigation. may change. Below the Kununurra Diversion Dam Power generation is restricted when storage levels in already parts of the river are not navigable. the lake are below-average, and some of the demand at the Argyle mine will be met through greater use of Navigational releases for Lake Kununurra are Water for the lower Ord River diesel generators. allowed if Lake Argyle storage levels are high and releases are consistent with the licence for dam The Ord River Dam has significantly changed the river environment. There As more water entitlements are granted for irrigation, operations. The practical arrangements for releases are now year-round flows in the lower Ord River from the diversion dam to the release rules will be adjusted to ensure enough are negotiated with and managed by the Water Mambi Island (66 km downstream), where tidal effects commence. This is in The Ord River Dam Water for irrigation water is retained in storage to provide water for Corporation. contrast with the drying-out periods that occurred naturally before the dam reliable irrigation supplies, hydropower demand and The Ord River Dam was built in the early 1970s to form Lake Argyle and Water for irrigation is either scheme- was built. environmental demands. Water released for irrigation When water levels in Lake Argyle are low or fall provide a reliable water supply to the Ord River Irrigation Area. The dam supplied by the OIC or self-supplied by and the environment can also be used to generate below the trigger levels for hydropower restrictions, The permanent flows over the dry season have altered the river environment captures highly variable runoff from the catchment each wet season and individual users. Up to 905 GL/year of hydropower, and releases solely for hydropower partly specific navigational releases from Lake Argyle and new water-dependent values have been established. stores it in Lake Argyle for later use. The storage enables water to be water entitlements can be granted from meet the lower Ord environment requirements. are not permitted. Releases made specifically for released year-round to generate hydro-electricity, supply downstream the existing infrastructure in the Ord area. enhancing boat navigation on the lower Ord River are While there is a lot of water flowing into the lower Ord now, water flows below irrigators in the irrigation season and sustain the lower Ord River Of particular importance to agricultural not feasible at these levels because they compromise the diversion dam will diminish as increased volumes of water are diverted for environment in dry periods. development is 750 GL/year from the hydropower generation and irrigation supply. agriculture. Main Ord subarea (using water from Lake Argyle’s capacity (to the full supply level) is 10 760 GL or 2.5 times Lake Argyle), which is simulated to be Scientific studies, including a low-flow trial, have been used to work out how the mean annual inflow. Carefully managed, it is sufficient to provide a highly available in 95 out of 100 years under the much water is needed to provide for habitat, fish movement and breeding, reliable water supply, even if inflows to the lake over three wet seasons are Department of Water Reservoir modelling. regeneration of vegetation, and dissolved oxygen. The environmental flow well below average. In July 2013, 400 GL/year of the regime provides a range of flows important for maintaining these river health 750 GL/year was available for new and ecological functions (see diagram below). The dam wall is high enough to capture the large volumes of flood waters of or increased entitlements to support the very wet seasons, and temporarily store them above the full supply level irrigation expansion. Subject to In most years, the environmental flows will be met by releases for hydropower (see Ord River Dam schematic below). The spillway, a deep narrow channel finalisation of intergovernmental and inflow from the catchment downstream of the Ord River Dam – cut through a rock saddle, is about seven kilometres from the dam wall. The agreements, there are also opportunities particularly from the Dunham River. In some years top-up releases will be spillway gradually discharges any flood water over the following dry season. for irrigation expansion in the Northern needed. As little or no flood water remains in storage by the next wet season, it does Territory. not contribute to the water that can be reliably supplied from Lake Argyle over When storage is low, releases for environmental flows will be reduced, extended drought periods. As agricultural developments expand, through restrictions described on the dam licence, to balance competing water must be managed and shared demands for water. responsibly to allow for dry years. There have been several years of severe drought during the past 100 years, and once water is fully allocated future dry periods could severely affect productivity and livelihoods. Given that climate models do not indicate a clear wetting or drying trend for the Kimberley area, the past 100 years’ climate was used as a basis to predict future climate and set water allocation limits and water release rules which provide a 95 per cent reliability for irrigation. During periods of low inflows water sharing is essential. Hydropower restrictions are applied to reduce the total demand on Lake Argyle before storage levels become very low (See Ord River Dam schematic) – Minimum operating level). If storage levels do become An example of the expected environmental flow regime for the lower Ord from very low, irrigation and environmental Lake Kununurra to Tarrara Bar Ord River Dam schematic restrictions also apply. How water is distributed from the Ord River and Kununurra Diversion dams