National Water Account 2020

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Key findings

Climate and water

Water Accounting Statements

Supporting information

Region description

Reference information

Ord: Region description

Geographic information

General information

Area: 65,800 km²
Population: 9,000 (Australian Bureau of Statistics [ABS] 2016)

Figure R1 Contextual map of the Ord region

• The Ord region is located in the East Kimberley region of Australia; the region overlaps the border between Western Australia and the Northern Territory.
• The boundary of the Ord region is physically defined by two surface water catchments: the Ord River and the Keep River.
• About 1.1% of Australia's water use occurs in the region. Most of the water use is from surface water for irrigation purposes.

Land use

Figure R2 Land use in the Ord region

• Kununurra is the regional centre; other towns include Halls Creek and Wyndham.
• Almost 80% of the region is used for pastoral grazing; about 20% of the region contains conservation areas, including national parks.
• 0.2% of the region contains irrigated agriculture, mainly in the Ord River Irrigation Area downstream of Lake Argyle. The major crops are sandalwood, mahogany, and a range of horticultural crops and grains.
• Mining areas make up 0.1% of the region and include Argyle Diamond Mine situated near Lake Argyle and nickel mining operations approximately 120 km north of Halls Creek.

Significant aquatic ecosystems

Figure R3 Significant wetlands in the Ord region

• The region contains several significant aquatic ecosystems, including Ramsar-listed wetlands.
• The Ord River and associated aquatic ecosystems have a strong cultural significance for a number of Aboriginal groups, particularly the Miriuwung and Gajerrong peoples (Barber and Rumley 2003).

Water resources

• Surface water resources support the main water users in the region, including irrigated agriculture, hydroelectric power generation, and self-supply licensees. Groundwater resources are primarily used for mine purposes and town supply.

Surface water

Storages

Figure R4 Major storages in the Ord region; capacity of each storage is also shown

• Lake Argyle is one of Australia's larger reservoirs. Water is released from the lake for hydroelectric power generation, and the resulting flows are used to supply downstream users and meet environmental water provisions in the lower Ord River.
• Most of the inflow into Lake Kununurra comes from water released from Lake Argyle. Lake Kununurra is primarily used to supply water to the Ord River Irrigation Area (see Irrigation scheme).
• Arthur Creek is a large private storage used for self-supply irrigation; Moochalabra is used for Wyndham's town water supply.

Rivers

• The Ord River, downstream of Lake Argyle, is regulated by releases of water from Lake Argyle to maintain flows in the lower Ord River. Self-supply licensees access the river for small-scale irrigation, industrial, commercial, and stock and domestic purposes.
• The upper Ord and Negri rivers are two primary rivers that flow into Lake Argyle. Limited diversions for consumptive use occurs in these catchment areas.

Figure R5 Key flow gauging stations along the main rivers within the Ord region

Figure R6 Mean monthly flows along the Ord (upper and lower) and Negri rivers and mean monthly rainfall for the Ord region

• Seasonal flow characteristics of rivers within the Ord region reflect the annual rainfall pattern of the region. Most of the rainfall occurs during the wet season (November–April). Consequently, most of the streamflow within the region occurs between January and May.
• Upstream of Lake Argyle, flows are very low or cease to flow during the dry season (May–October). The Ord River below Lake Argyle receives specific releases to maintain minimum environmental flows in the lower Ord River. Consequently, flow in the lower Ord River is perennial.
• Other rivers in the Ord region exhibit seasonal flow patterns similar to rivers upstream of Lake Argyle.

Groundwater

• Groundwater resources in the region are not extensively developed.
• Borefields in localised fractured rock aquifers are used for urban supply to Halls Creek and mining operations in the upper reaches of the Ord region.
• Sedimentary aquifers adjacent to Lake Kununurra are used to supply the town of Kununurra.

Water systems

Irrigation scheme

Figure R7 Ord River Irrigation Area

• The Ord River Irrigation Area comprises an open canal network that is used to distribute water for irrigated agriculture.
• Water supplied to the Ord River Irrigation Area represents more than 90% of the total surface water entitlements in the region.
• Water is diverted from the Ord River at Lake Kununurra. Most of the irrigation water is diverted via the M1 supply channel to the Ivanhoe Plain and Goomig Farmlands; less than 10% is diverted to the Packsaddle Plain (Department of Water 2013)
• Areas of proposed irrigation expansion within the Ord region are described in Major water reforms in 'Climate and water'.

Water management

Surface water and groundwater management

Water legislation

• The Western Australian Rights in Water and Irrigation Act 1914 and the Northern Territory Water Act 1992 establish the framework for managing and allocating water resources in the Ord region.
• The Western Australian Department of Water and Environmental Regulation and the Northern Territory Department of Environment and Natural Resources assist their respective ministers with the functions set out in the Acts, including proclaiming water management areas and regulating the taking of water from these areas.

Figure R8 Surface water management areas in the Ord region

Figure R9 Groundwater management areas in the Ord region

• Three surface water management areas and one groundwater management area proclaimed under the Rights in Water and Irrigation Act 1914 exist in the portion of the region within Western Australia.
• No management areas exist in the portion of the region that lies within the Northern Territory.

Water allocation plans

• The Department of Water and Environmental Regulation prepared the Ord Surface Water Allocation Plan, which sets out how the department allocates and licenses surface water in the region to manage the demands of irrigation, hydroelectricity generation, and urban and individual supply.
• The plan also recognises the area's environmental values and ensures that sufficient water is retained to protect aquatic ecosystems and meet specific social and cultural needs.
• Water management plans and allocation plans have not been developed for groundwater resources in the region due to the limited use of groundwater compared to the availability.

Environmental water management

• The Environmental Water Provisions Policy for Western Australia guides the Department of Water and Environmental Regulation in water allocation planning and decision-making in relation to allocating water to the environment.
• The Ord Surface Water Allocation Plan defines environmental water provisions to protect the ecological condition of the lower Ord River.
• The Water Corporation of Western Australia has an obligation to manage releases from Lake Argyle and Lake Kununurra to maintain specific flow rates in the lower Ord River. The Department of Water and Environmental Regulation monitors flows at key locations in the lower Ord River to ensure that water regime requirements are met.
• Further information regarding environmental water provisions for the 2019–20 year is provided in the Cultural and environmental water note in 'Supporting information'.

Cultural water management

• The Ord Surface Water Allocation Plan defines cultural water provisions that consider the Miriuwung and Gajerrong peoples' interests along the lower Ord River.
• Short periods of low ('dry out') flows are important to Dreaming stories of the Miriuwung and Gajerrong peoples. Since dam construction, such 'dry out' flows in the lower Ord River are rare and generally only occur when maintenance or inspection work is carried out at the dams.
• The Department of Water and Environmental Regulation and the Water Corporation have an obligation to let the Miriuwung and Gajerrong peoples know when such work is undertaken so that traditional activities can be pursued during these periods.

Organisations responsible for water management

• Organisations responsible for water management in the region are shown below.

Water rights

Operating rules and constraints

• The Department of Water and Environmental Regulation control the taking of water through water allocation planning and licensing arrangements. Water can only be taken from designated water management areas within the region when a licence is issued.
• Chapter 5 of the Ord Surface Water Allocation Plan defines the rules and conditions that apply to water licences for hydroelectricity generation, irrigation, the environment, and self-supply. The plan also outlines how water is managed during drought years, as well as potential modifications to rules as irrigation demands on water increase in the next few years (see Major water reforms in 'Climate and water').

Water entitlements and other statutory water rights

• The Department of Water and Environmental Regulation administer water licences that usually specify the conditions, length of tenure, and the maximum volume of water that may be taken, referred to as the water entitlement.
• Under the Rights in Water and Irrigation Act 1914, the Water Corporation holds a licence that regulates its operation of the Ord River Dam and the Kununurra Diversion Dam. The licence sets conditions on how water may be released from the storage for hydroelectricity generation and obliges the Water Corporation to operate storage levels so that the environmental water provisions for the lower Ord River are maintained.
• Also under the Act, the Ord Irrigation Cooperative Limited holds a licence for the diversion of water from Lake Kununurra. The licence is issued for the purposes of distribution and supply to irrigators for irrigation use and for nonpotable commercial uses in areas serviced by the Stage 1 channel systems of the district.

Water allocations

• The Ord Surface Water Allocation Plan area covers the Western Australian part of the Ord region. To best set environmental water provisions and water entitlement limits, the Department of Water and Environmental Regulation subdivided the plan area into five subareas based on infrastructure and river channel morphology.

Figure R10 Annual water entitlements for surface water resource areas of the Ord region

• The current annual water entitlement is 905,000 ML/year. More than 95% of these water entitlements are from the Main Ord River and Carlton–Mantinea subareas downstream of Lake Argyle. No water entitlements are granted directly from the Tarrara–Carlton subarea as there is no provision for any developments and the soils and topography are not favourable for irrigation.
• Annual water allocations are the quantity of water available after environmental water provisions and domestic requirements are met and are determined and announced by the department in April each year.
• Groundwater entitlements are also administered by the department and these include allocations for the town supply of Kununurra and Halls Creek.

Trades and water rights transfers

• The Act permits the trading or transferring of licences but only within the same water management area and subject to compliance with the other conditions of the Act and other administrative issues. Trades or transfers cannot be made between different water management areas.
• Members of the Ord Irrigation Cooperative Limited can trade their water allocations within the irrigation area in accordance with the cooperative's rules, provided both trading parties are members of the cooperative. Members are prevented from trading water directly with parties outside the cooperative. For more detail please refer to the Ord Irrigation Cooperative Limited website.