NT Por 2532

Daly River - Oolloo Crossing

Daly River - Mount Nancar

Daly River - Dorisvale Crossing

Zone 1Zone 2

SouthernZone

CentralZone

NorthernZone

Culle

nRive

r

Dry River

Driffiel dCr eek

Flora River

Bamboo (Moon Boon)Cree k

Seven

teen Mile

Cre

ek

Katherine River

Bradshaw Creek

Pa lm Cree k

Daly River

Edith River

Sco tt Creek

MuldivaCreek

King Rive

r

Fish River

Limestone C reek

Mathison

Creek

McaddensCreek

Wandie Creek

Stray C reek

Chillin

g Cree

k

Fergusson River

Douglas River

Hayward Cr

ee

k

Ikymbon River

Pine Creek

Copperfield Creek

Aroona Cree

k

Victoria Hwy

Stuart Hwy

Stuart Hwy

Kakadu Hwy

Buntine Hwy

Pine Creek

Katherine

132°20'E

132°20'E

132°0'E

132°0'E

131°40'E

131°40'E

131°20'E

131°20'E

131°0'E

131°0'E

130°40'E

130°40'E14°

0'S

14°0'S

14°20'

S

14°20'

S

14°40'

S

14°40'

S

15°0'S

15°0'S

15°20'

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15°20'

S

© Northern Territory of Australia

Locations ofNew GWEL Entitlement

DATA SOURCE:Water Resources: Dept Land Resource ManagementCadastre/Roads/Placenames:Dept Lands, Planning and EnvironmentDrainage: 250K © Commonwealth of Australia (BoM) 2012

Legend - Water ManagementNew GWEL Extraction PointExisting GWEL Extraction PointExisting SWEL Extraction PointGauge StationOolloo Dolostone (Draft) WAP AreaOolloo Dolostone (Draft) WMZKatherine Tindall Limestone WAP AreaKatherine Tindall Limestone WMZDaly Roper Water Control District

Map compiled: 29/04/2016Policy and Planning Group, Water Resources Division

Department of Land Resource Management

Land Parcel: New/Increased GWEL ApplicationGeological Formations - Daly Basin

Tindall Limestone, unconfinedTindall Limestone (150m bgl), confinedJinduckin FormationOolloo Dolostone (Bedded Unit)Oolloo Dolostone (Massive Unit)Florina Formation

WAP - Water Allocation PlanWMZ - Water Management Zone (within the Plan)GWEL - Groundwater Extraction LicenceSWEL - Surface Water Extraction Licence

Legend - Other

Attachment BStatement of Decisions for New or Increased

Groundwater Extraction LicencesNT Por 2532

Darwin

Katherine

Pine Creek

Map Extent within theDaly Roper Water Control District

Darwin

Katherine

Pine Creek

0 100 200 km

Horizontal Datum:Geocentric Datum of Australia (GDA94)

0 10 20 30km km

Attachment C – The Department’s approach to assessing water extraction licence applications

Background Groundwater extractions from the Tindall Limestone Aquifer and the Oolloo Dolostone aquifer have the potential to impact on flows in the Katherine and Daly Rivers. When assessing new licences, consideration is given to:

• the Northern Territory Water Allocation Framework;

• the declared Tindall Water Allocation Plan, Katherine;

• the draft Oolloo Aquifer Water Allocation Plan; and

• the connected and cumulative nature of potential impacts from existing and new water extraction licences.

Underpinning the assessment are the tools and management criteria that have been developed for the Daly Basin aquifers and the Daly River Catchment over the last 10 years. These tools and management criteria have informed the development of the existing declared and draft in progress Water Allocation Plans:

• The integrated groundwater and surface water models for the Daly River Catchment which provide coordinated accounting of all water extractions throughout the Daly River catchment including existing licensed and unlicensed uses.

• Northern Territory Water Allocation Planning Framework, which was included in the Implementation Plan for the National Water Initiative that was accredited by the National Water Commission in 2006 (see annex A).

• The Environmental Water Requirements of the Daly River developed in consultation with expert advice, department staff and the Daly River Community Reference Group (Erskine et al. 2004). The report can be found at: http://www.territorystories.nt.gov.au/bitstream/10070/229248/1/WRD04030.pdf

• The declared Tindall Limestone Aquifer, Katherine Water Allocation Plan and the draft in-progress Oolloo Aquifer Water Allocation Plan. Both these plans were developed in consultation with community members and relevant stakeholders and were informed by the models and the environmental water requirements report described above.

Overview of the modelling undertaken Licences are issued for a period of 10 years. Estimated water availability for atleast the next 10 years is based on river flows over the last 30 years. This approach is considered the best approach by the department.

Each new licence application was assessed using the integrated surface water and groundwater models to develop an understanding of how flows in the Flora and Daly Rivers are likely to be altered as a result of the extractions sought for each new licence.

The model results were assessed against the environmental flow requirements of the Daly River and Flora River for the 30 year period since 1986. Put another way, the modelling approach enables us to investigate the following question:

If all existing licences plus each new additional licence were extracted at their maximum entitlement for 30 years, under the same aquifer recharge and river flow conditions that have been observed over the last 30 years, what would the flow in the river be, and would this flow be acceptable for the maintenance of existing licence reliabilities and environmental flow requirements?

The modelling of each licence was undertaken sequentially in order of the date each application was finalised and accepted. Thus, the modelling assessment scenarios were as follows:

• Baseline scenario - natural river flows (i.e. no extractions).

• Existing entitlement scenario (i.e. all licensed and unlicensed extractions prior to the determination of the new licence applications)

• Five sequential new licence scenarios:

Scenario a): Existing entitlements plus new entitlement for NT Portion 2978

Scenario b): Scenario a) plus new entitlement for NT Portion 2530

Scenario c): Scenario b) plus new entitlement for NT Portion 709

Scenario d): Scenario c) plus new entitlement for NT Portion 2532

Scenario e): Scenario d) plus new entitlement for NT Portion 1166 & 4305

Environmental Flow Criteria The environmental flow criteria used to assess the availability of water for the newly proposed licences are outlined below.

Consistent with the environmental water requirements of the Daly River (Erskine et al. 2004), the combined effect of all groundwater and surface water extractions should not reduce natural flows in the Daly River:

(a) at Dorisvale Crossing gauge station G8140067 by (i) >8% whenever natural flow is ≤6.2 cubic metres per second; or (ii) >20% whenever natural flow is >6.2 cubic metres per second

(b) at Oolloo Crossing gauge station G8140038 by

(i) >8% whenever natural flow is ≤12 cubic metres per second; or (ii) >20% whenever natural flow is >12 cubic metres per second

(c) at Mount Nancar gauge station G8140040 by

(i) >8% whenever natural flow is ≤12 cubic metres per second; or (ii) >20% whenever natural flow is >12 cubic metres per second

As specific scientific work has not been undertaken to develop environmental flow triggers for the Flora River, and consistent with the Northern Territory Water Allocation Planning

Framework, the combined effect of all groundwater and surface water extractions should not reduce natural flows at Flora River gauge station G8140205 by more than 20%.

Reliability Analysis Reliability is the estimate of how many years the licence volume would be available in full without reducing natural flows by more than the change allowed by the environmental flow criteria on any given day in any year for the period 1986 to 2015.

Annual announced allocations operate to limit licensed extractions in years when predicted flow reductions in the river exceed the environmental flow criteria for the Daly River and Flora River.

Analysis of impacts to flow in the Daly River

There has been a significant change to the way that reliability is estimated using the modelled river flow data. In December 2015, Water Resources Division staff undertook an audit of the predicted versus observed natural flows for the Daly river at Dorisvale Crossing, Oolloo Crossing and Mount Nancar. This audit was undertaken as part of the quality assurance checking of model predictions used for decision making. The model provides sound estimates of the reduction in river flows caused by surface water and groundwater extractions. However, the audit found that estimates of actual river flows are generally greater than the monitored data available for the Daly River at Dorisvale Crossing gauge station (G8140067) and Mount Nancar gauge station (G8140040). At Oolloo Crossing gauging location, G8140038, it was found that the model tends to slightly over-predict river flow when the observed flow is below 20 cumecs.

As such, in order to avoid overestimating reliability based on modelled Daly River flows, the predicted flows at Dorisvale Crossing and Mount Nancar were analysed in the following way:

• The cumulative change in flow resulting from each new licence operating at maximum extraction level for the period 1986 to 2015 was calculated for each day.

• The change in flow was assessed against measured flows at Dorisvale Crossing and Mount Nancar rather than modelled natural flows.

• Modelled change in flow divided by measured flow in the Daly River at Dorisvale Crossing and Mount Nancar was expressed as a percentage on each day for the period 1986 to 2015. The licence reliability is then determined by comparing the percentage change for each day to the environmental flow requirements at each site.

Unlike the measured flow record at Dorisvale Crossing and Mount Nancar, a long record of continuous, rated, flow data is not available at Oolloo Crossing. However, regular gaugings which measure stream flow are collected at least twice a year. Data pairs of stream flow gaugings and modelled flows were used to derive a correlation between modelled natural and measured natural flows. This correlation was used to adjust modelled flows at Oolloo Crossing to achieve more conservative estimates of modelled natural and modelled altered flows. Modelled change in flow divided by modelled natural flow at Oolloo crossing was expressed as a percentage on each day for the period 1986 to 2015. The licence reliability was then determined by comparing the percentage change for each day to the environmental flow requirements at Oolloo Crossing.

Previously, reliability had been estimated using modelled flows only, i.e. at all gauging stations, the percentage change in flow was estimated by the difference in modelled flows for the natural (no pumping) and altered (with pumping) scenarios, divided by the modelled natural flow. The outcome of changing the way reliability is analysed, is that reliabilities for all existing licences and for the newly granted licences is lower than was previously estimated. The finding resulted in readvertising of the Notices of Intention to Make a Decision in December.

An independent review of the approach used to estimate licence reliability was sought by the Controller of Water Resources in early 2016 to assure the Controller that the method neither put the environmental and cultural values of the Daly River at risk, or injudiciously restricted the volume of water that can be expected to be sustainably extracted from the aquifers for non-consumptive beneficial uses. The review confirmed that the approach is appropriate for the determination of licence reliabilities which underpins the decision about whether water is available for granting additional licences.

Analysis of impacts to flow in the Flora River

There has been limited model calibration in the Flora region of the integrated Daly Basin model due to a lack of hydrological information. A new gauging station (G8140205) was installed and data collection commenced in 2009, providing measurements from 6 dry seasons that have been used to implement model calibration in the lower reach of the Flora River. The model will be continuously improved as more data is collected in the region.

Using the existing model, predictions of the likely change to streamflow resulting from granting the new licence on NT Portion 2978 have been made. Modelled change in flow at gauging station G8140205 was assessed against modelled natural flow and expressed as a percentage for each day for the period 1986 to 2015. The resulting changes to daily flows are very low (between 0% and 1%).

These results are as expected, due to the relatively low licence volume (1,868 ML/year), and its location in the unconfined part of the Tindall Limestone, approximately 100 km south-east from the Flora River. The distance from the Flora River results in attenuation of drawdown by the groundwater system well before it is possible to impact flow the Flora River. It is also worth noting that there are no other water extraction licences located in the Tindall Limestone Aquifer, Flora recharge area.

ANNEX

NORTHERN TERRITORY WATER ALLOCATION PLANNING FRAMEWORK All available scientific research directly related to environmental and other public benefit requirements for the water resource will be applied in setting water allocations for non-consumptive use as the first priority, with allocations for consumptive use made subsequently within the remaining available water resource. In the absence of directly related research, contingent allocations are made for environmental and other public benefit water provisions and consumptive use. These are explained below. Top End (northern one third of the Northern Territory) Rivers At least 80 per cent of flow at any time in any part of a river is allocated as water for environmental and other public benefit water provision, and extraction for consumptive uses will not exceed the threshold level equivalent to 20 per cent of flow at any time in any part of a river. In the event that current and/ or projected consumptive use exceeds the 20 per cent threshold level, new surface water Licences will not be granted unless supported by directly related scientific research into environmental other public benefit requirements. Aquifers At least 80 per cent of annual recharge is allocated as water for environmental and other public benefit water provision, and extraction for consumptive uses will not exceed the threshold level equivalent to 20 per cent of annual recharge. In the event that current and/ or projected consumptive use exceeds the 20 per cent threshold level, new groundwater Licences will not be granted unless supported by either directly related scientific research into groundwater dependent ecosystem/ cultural requirements, or in the absence of such research, hydrological modelling confirming that total groundwater discharge will not be reduced by more than 20 per cent. Arid Zone (southern two thirds of the Northern Territory) Rivers At least 95 per cent of flow at any time in any part of a river is allocated as environmental and other public benefit water provision, and extraction for consumptive uses will not exceed the threshold level equivalent to five per cent of flow at any time in any part of a river. In the event that current and/ or projected consumptive use exceeds the threshold levels of five per cent for river flow, new surface water Licences will not be granted unless supported by directly related scientific research into environmental other public benefit requirements. Aquifers There will be no deleterious change in groundwater discharges to dependent ecosystems, and total extraction over a period of at least 100 years will not exceed 80 per cent of the total aquifer storage at start of extraction. In the event that current and/ or projected consumptive use exceeds the threshold levels of 80 per cent of the consumptive pool for aquifers, or groundwater discharges to groundwater dependent ecosystems are impacted, new groundwater Licences will not be granted unless supported by directly related scientific research into groundwater dependent ecosystem/cultural requirements.