Ord: Water access and use
Water rights, entitlements, allocations and restrictions
Introduction
This note provides information about the water access rights granted by jurisdictions to the users of the region's water resources and the associated allocation announcements and abstractions.
The 2015 Account acknowledges that the legislative water resource management frameworks relating to Australian water rights vary greatly across jurisdictions, sometimes making comparisons difficult. To facilitate meaningful comparisons between the 2015 water accounting reports, the Bureau of Meteorology has developed and applied an accounting concept to classify and report water entitlements within a water asset/water liability framework.
According to that framework, water rights for the Ord region for the 2014–15 year have been classified as shown below.
Surface water rights
Surface water rights in the Ord region during the 2014–15 year refer to surface water supply for:
- individual users—37,612 ML
- urban water system—775 ML
- irrigation scheme—459,800 ML.
Surface water rights for the urban water system and the irrigation scheme relate to entitlements to divert water for town supply (Wyndham and Lake Argyle Village) and the Ord River Irrigation Area respectively.
In the Ord region, surface water allocations were equal to 100% of the water access entitlement.
The volumes of surface water allocation and diversion for the 2014–15 year compared with the 2013–14 year are shown in Figure N18. The percentage shows the ratio of diversion to the allocation announcement.
Figure N18 Surface water allocations and diversions in the Ord region for the 2013–14 and 2014–15 years
Figure N18 shows that the allocations for surface water diversion to the irrigation scheme during the 2014–15 year were much larger than the previous year. This is attributed to a new licence being issued to the Kimberley Agricultural Investment Pty Ltd in mid-2015 for water diversion to the Goomig Farmlands. The allocation associated with this new licence is 120,000 ML. The actual diversions to the Ord River Irrigation Area during the 2014–15 year increased slightly compared to the previous year (Figure N18). This can be partly attributed to the additional water diversions to the Goomig Farmlands at the end of the year, and partly to the below average rainfall conditions during the wet season (see Climate and water overview).
Surface water allocations for individual users and urban water supply remained relatively unchanged from the 2013–14 year. The allocated diversions to individual users during the 2014–15 year decreased slightly from the previous year; however, this was because metered diversion data were available for two mining licences this year. Last year, these data were not available and it was assumed that diversion was equal to the allocation announcement. Diversions for urban water supply also decreased slightly from the previous year.
There are approximately 100 individual users in the region that primarily source water from the main Ord River channel, upper Ord River, Dunham River and King River for agricultural and mining purposes. The water supply licences are divided into licence entitlement purposes. Figure N19 shows the annual allocation to individual users for each licence purpose for the 2014–15 year changed little from that of the previous year.
Figure N19 Surface water allocation to individual users for each licence purpose for the 2014–15 and 2013–14 years
Groundwater rights
Groundwater rights in the Ord region during the 2014–15 year refer to groundwater supply for:
- individual users—11,506 ML
- urban water system—2,700 ML.
Groundwater rights for the urban water system relate to entitlements to extract water for town supply (Kununurra and Halls Creek).
In the Ord region, groundwater allocations were equal to 100% of the water access entitlement.
The volumes of groundwater water allocation and extraction for the 2014–15 year compared with the 2013–14 year are shown in Figure N20. The percentage shows the ratio of extraction to the allocation announcement.
Figure N20 Groundwater allocations and extractions in the Ord region for the 2013–14 and 2014–15 years
Figure N20 shows that the allocations for groundwater extraction for individual users during the 2014–15 year increased slightly compared with the previous year; however, extractions to individual users decreased. This decrease is because metered extraction data were available for one of the large mining licences this year. Last year, these data were not available and it was assumed that extraction was equal to the allocation announcement.
Allocations and extractions for urban water supply remained relatively unchanged.
There are approximately 40 individual users in the region who primarily source water from the Canning–Kimberley groundwater area for the mining sector. The water supply licences are divided into licence entitlement purposes. Figure N21 shows the annual allocation to individual users for each licence purpose for the 2014–15 year changed slightly compared with the previous year—allocations for agricultural purposes increased and allocations for the commercial and institutional sector decreased.
Figure N21 Groundwater allocation to individual users for each licence purpose for the 2014–15 and 2013–14 years
Water restrictions
There were no water restrictions in the Ord region during the 2014–15 year.
Water market activity
In Western Australia, water entitlement trades and transfers can only occur within the same water management area (see the Trades and water rights transfers section in the 'Contextual information').
Trades and transfers are defined as water entitlements that are permanently transferred to another licence holder. A trade is where the new licence holder will abstract water from a different location; a transfer is where water abstraction will occur from the same location. An agreement is a temporary transfer of a licence water entitlement to another licence holder (also referred to as a temporary transaction). More information on water entitlement transactions can be found on the Department of Water website.
During the 2014–15 year, one water entitlement transfer of 70 ML occurred in the Ord region; no trades of groundwater licence entitlements occurred during the year.
Water use
Economic, social and cultural benefit
Water is released from Lake Argyle for hydroelectric generation. The power station requires enough water released to enable at least 210 gigawatt hours/year to be generated (see the Operating rules and constraints section in the 'Contextual information'). To generate this power commitment, about 2,100,000 ML/year must be released from Lake Argyle. The water released has the dual purpose of administering water access entitlements downstream, including bulk irrigation in the Ord River Irrigation Area, and other agricultural, commercial, industrial, and mining activities.
For a summary of the water volumes allocated for various economic purposes within the Ord region, including the actual volumes abstracted, refer to Surface water rights and Groundwater rights above.
Water provided for the environment to maintain specific levels in the lower Ord River has the dual purpose of satisfying ecological requirements and allowing access to boats for recreational purposes.
Periods of low flow in the lower Ord River are administered to support traditional hunting and fishing activities (see the Cultural water management section in the 'Contextual information'). This occurs from time to time when maintenance and inspection work on dam infrastructure is required. During the 2014–15 year, Lake Kununurra was lowered for routine inspections and maintenance from 31 January–15 February. Consequently, flow in the lower Ord River was reduced during this period (see Figure N23 in the 'Environmental benefit' note).
Environmental benefit
Environmental water legislation
Environmental water provisions in the Ord region are defined for the lower Ord River (downstream of Lake Argyle). These provisions are outlined in the Ord Surface Water Allocation Plan.
The plan outlines a flow regime required to maintain current ecological conditions in the lower Ord River, including:
- populations of fish and macro invertebrates
- vegetation community structure
- water quality
- channel morphology.
The plan recognises that different parts of the flow regime, such as low, high and overbank flows, have different ecological functions. The different components of the flow regime, which reflect the seasonality of the river, are important to the ecology of the lower Ord River.
Environmental water provisions
Environmental water provisions for the lower Ord River comprise three components:
- baseflow (minimum flow rate)
- wet season flood events
- infrequent (high magnitude) wet season flood events.
All three components of the flow regime are critical for maintaining ecological conditions in the Ord River. The required flow regimes are maintained from a combination of water releases from Lake Argyle and Lake Kununurra, and unregulated catchment inflow.
The Water Corporation operates the two storages and manages the releases of water. The Department of Water monitors the flow along the lower Ord River at the Tarrara Bar gauging station (Station 809339—see Figure C7 in the 'Contextual information' for location) to ensure the required flow is being maintained throughout the year.
The required minimum baseflow in the lower Ord River varies between the wet and dry seasons. Figure N22 shows the required baseflows at the Tarrara Bar station throughout the year; the minimum baseflow is 42 m3/s. Baseflow during the dry season (April–October) is managed almost entirely by water releases from the storages. Figure N22 also shows the frequency, duration, and peak flows required for the wet season flood events in the lower Ord River.
Figure N22 Example water provisions for the lower Ord River; required baseflows and wet season flood events are also shown
The infrequent wet season flood events occur as a result of runoff from the catchment downstream of Lake Argyle and cannot be managed by water releases from the storages. The return intervals for these flood events are greater than 1 in 2 years, so this component of the required flow regime is difficult to evaluate on an annual basis. These flood events are not shown in Figure N22 above.
A more detailed description of the environmental water provisions for the lower Ord River are provided in Chapter 4 of the Ord Surface Water Allocation Plan, including variations to the flow regimes for low rainfall years (determined by water levels in Lake Argyle).
Environmental water outcomes
The mean daily flow at the Tarrara Bar gauging station along the lower Ord River during the 2014–15 year is shown in Figure N23.
For all but three days of the year (9–11 February 2015), flow in the lower Ord River exceeded the minimum baseflow requirements. This 3-day period of low flow coincided with dam maintenance and inspection work at Lake Kununurra (see Economic, social and cultural benefit above).
Figure N23 also shows that wet season peak flows met the requirements outlined in the water provisions.
Figure N23 Flow in the lower Ord River compared with the required flow regime during the 2014–15 year
Infrequent wet season flood events are the third component of the flow regime critical for maintaining ecological conditions in the lower Ord River (see Environmental water provisions above). One flood peak on 5 January 2015 met the required 1 in 2-year flood event (average daily discharge >750 m3/s). Flood peaks which met the required 1 in 4- and 1 in 27-year flood events (average daily discharge >1,400 m3/s and >3,700 m3/s respectively) occurred during the previous wet season (see the 2014 Account).