[PPT] - 2019- 20 River Operations Stakeholder Consultation Committee PowerPoint Presentation

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Lachlan River Operations 2019- 20

River Operations Stakeholder Consultation Committee (ROSCCo) 19 May 2020

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WaterNSW

Recent Rainfall

1 Feb to 30 Apr

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WaterNSW

Recent rain hydrographs

76,000 ML 44,000 ML

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WaterNSW

Recent rain hydrographs

17,000 ML 13,000 ML 2,500 ML 2,500 ML

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WaterNSW

Recent rain hydrographs

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Current Storage Status

Wyangala: as at 15 May 20
Storage Volume: 178,885 ML
Storage Percent: 14.6%
System Inflows since 1July19 – 31 Jan 20: 9,700 ML
System Inflows since 1Feb 20 – 15May 20:154,000 ML(115+39 GL)
Lake Cargelligo:
Storage Volume: 30,962 ML
Storage Percent: 81.5%
Lake Brewster:
Storage Volume: >18,000 ML
Storage Percent: 12.8%

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Wyangala Dam Operations

0% 20% 40% 500 1000 1500 2000 2500 3000 3500 4000 01-Jul-19 11-Jul-19 21-Jul-19 31-Jul-19 10-Aug-19 20-Aug-19 30-Aug-19 09-Sep-19 19-Sep-19 29-Sep-19 09-Oct-19 19-Oct-19 29-Oct-19 08-Nov-19 18-Nov-19 28-Nov-19 08-Dec-19 18-Dec-19 28-Dec-19 07-Jan-20 17-Jan-20 27-Jan-20 06-Feb-20 16-Feb-20 26-Feb-20 07-Mar-20 17-Mar-20 27-Mar-20 06-Apr-20

Dam Level in % Flows in ML/d

Lachlan River Operation 2019-20

Dam Inflows (Monthly) Dam Release Extractive Orders_Upper Lachlan Dam Level 'spring pulse' To maintain levels in Lake C and Brewster WR

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Comparison of Drought inflows

Aug 2017 – May 2020 (34 months) actual dam inflows = 365 GL
Aug – May (34 months) pre 2004 DOR inflows = 532 GL (year 1947)
Aug – May (34 months) millennium DOR inflows = 263 GL (year 2005)

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Stage Water quantity Water quality Stage 1 Normal management Continue to deliver water as normal Raw water can be treated with usual methods Stage 2 Emerging water shortage Operational surface water measures to conserve supplies Potential or actual impacts on groundwater Minor adjustments to treat raw water Stage 3 Severe water shortage Restrictions on water for:

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High priority licences

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General security licences Unacceptable groundwater impacts Major adjustments are needed to treat raw water Stage 4 Critical water shortage Water only available for critical human needs Restrictions on all licences Risk to long term availability of the groundwater resources Not possible to treat raw water with standard processes Raw water likely to remain untreatable over the longer term

Extreme event stages

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Water Account Summary

30 April 20 Sum of Share Component Sum of Account Balance Sum of Available Water Sum of AWD Vol Sum of Carryover In Sum of Allocation Assignments In Sum of Allocation Assignments Out Sum of Usage DOMESTIC AND STOCK 10,954 7,273 7,170 10,949

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8 8 3,669 DOMESTIC AND STOCK [DOMESTIC] 176 173 173 176

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DOMESTIC AND STOCK [STOCK] 1,599 1,407 1,407 1,599

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190

LOCAL WATER UTILITY 15,545 8,254 8,148 15,545

7,291

REGULATED RIVER (CONVEYANCE) 17,911 107 107 6,960

6,853

REGULATED RIVER (Irrigation GS) 469,309 49,823 12,422

83,278

14,063 23,245 24,362 REGULATED RIVER (Environment GS) 123,492 42,108 8,041

71,609

11,007 32,221 8,286 REGULATED RIVER (Irrigation HS) 24,952 8,628 8,307 20,574

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23,048 12,815 23,302 REGULATED RIVER (Environment HS) 2,728 289 289 2,373

22,348

2,183 22,249 Grand Total 666,667 118,061 46,063 58,176 154,861 70,473 70,473 96,205

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WaterNSW

Likely Scenario-2020-21 (scenario 4)

15 GL of GS used
> 70% AWD for HS (19 GL)
100% AWD for Town & S&D

(17 GL)

IRG 3 operations requiring

130 GL with drought contingency measures

No S&D Replenishment from

dam or Lakes

Cease to Flow May 2021
Inflow of 40 GL is required

by end October 2020 for unrestricted full year delivery and to hold 3% in Wyangala Dam at end of 2020-21

End April 2020 assessment

14.7% 11

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Likely Water Availability in 2020-21 -

Water Allocation Statement of May 2020

Towns and S&D – 100% AWD
High Security – min. 70% AWD
Conveyance Licence - commensurate allocation
General Security – zero AWD
General Security – 50% of usable allocations remaining on

30 June 2020 (est. at 29 GL x 50% = 14.5GL)

S&D replenishment flows – not from storages
ECA – zero
WQA – 10 GL assessed as likely use in 2020-21

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River Operations Under IRG 3

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WaterNSW

What Does it take to operate Lachlan River

Transmission and Operation Loss

Regulated Lachlan River Transmission & Operations Losses Typical dry year (GL) Millennium Drought IRG stage 3 drought

perations

IRG stage 4 drought

perations

2004-05 2006-07 2008-09

Main regulated river from dam to Lake Cargelligo Weir

56 27 76 59 55 55

Wallamundry/Wallaroi/Nerrathong system

14 14 13 12 12 6

Replenishment flows into Booberoi Ck

12 7 7 6 6 3

Flows to Lake Cargelligo through emergency works for TWS & BLR

5 3 3 3 3

Losses in regulated Willandra Ck system

15 4 2 2 2

Losses LC Weir to Booligal

40 42 47 40 39 20

Target Flows required below Booligal

13 15 15 14 13 6

Replenishment Flows into Willandra Creek

9 5

Replenishment Flows into Merrowie Creek

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Replenishment Flows into Merrimajeel/Muggabh Creek

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Operational Surplus

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Total

180 118 163 135 130 95

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WaterNSW

Resource Availability/Distribution end of April 2020

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Drought Contingency Measures – to continue into 2020-21

Willandra Creek (regulated) - ceased to flow to continue
Wallamundry System - reduced flows to block releases in summer and at

times ceased to flow in lower sections

Island Creek Fishway – may require approval to close in summer
Reduced End of System Target flow at Booligal
Booberoi Creek – current ceased to flow to intermittent flows later
No delivery of S&D Replenishment from Wyangala or Lakes
Lake Cargelligo – potential offline from Lachlan River from 1 November
Active reregulation from Gonowlia and Torriganny Weirs

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Combined inflows to deliver 29 GL GS & begin to ease drought account

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AWDs during millennium drought in %

Year HS LWU S&D GS 2004-05 30 50 30 2005-06 100 100 100 19 2006-07 30 80 80 2007-08 30 70 50 2008-09 30 70 50 2009-10 10 50 15

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Potential for triggering of translucent flows during drought contingency
perations
Relative water availability for HS and GS under drought contingency

measures – should HS AWD be lower than 70% to allow access to more

f the remaining usable GS allocations
Needs of water allocations for critical industries
Water demand from the lakes in the coming season
Drought contingency measures – impacts and other ideas
Implementation of alternate water supplies from GW for towns before

ceased to flow at Wyangala Dam

Discussions and Recommendations

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Planned Outage

Wyangala Dam Outlet works (penstock): June – July 20 (5 weeks)

– Dam releases via bypass penstock, max 300 ML/d

Jemalong Weir Gate Maintenance: June – July 20 (4 weeks)

– Weir pool drained to river levels

Lake Cargelligo Inlet Regulator – Rehabilitation work date TBA

– Dry work site with block bank in u/s

Booberoi Creek channel - Desilting work date TBA

– Dry channel with block bank at the offtake

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Climate Outlook

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Wyangala Dam Raising

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Wyangala Dam Raising

For more info visit WaterNSW website:

https://www.waternsw.com.au/projects/new-dams-for-nsw/wyangala-dam

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WaterNSW

Visit the website at:

waternsw.com.au/drought

For information on the Macquarie Valley including water availability reports and drought reports go to: waternsw.com.au/supply/drought-information/regional- nsw/macquarie-valley Call us on:

1300 662 077

Subscribe at:

waternsw.com.au/subscribe

For weekly customer drought updates and more information

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To keep updated

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WaterNSW 25

Thank you for joining us today

WaterNSW

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WaterNSW

Assumptions:

Zero inflows
Water savings 15 GL in

2019-20

2020-21under IRG 3

Essential Requirements – 130GL

GS under usage – 10 GL
WQA – 1GL
No S&D replenishment
Lake Cargelligo Offline

March 2020

End January 2020 assessment

4.2% 1.6%

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WaterNSW

End January 2020 assessment with February inflows

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WaterNSW

Wyangala Dam Behaviour during Millennium Drought 2003-2010

0% 5% 10% 15% 20% 25% 30% 35% 40% 45%

50000 100000 150000 200000 250000 300000 350000 400000 450000 01-Jul-03 01-Jul-04 01-Jul-05 01-Jul-06 01-Jul-07 01-Jul-08 01-Jul-09 01-Jul-10

Wyangala Dam Storage Volume During Millennium Drought 2003 - 2010

Wyangala Volume (ML) Wyangala Level (%)

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WaterNSW

Potential Scenarios Considered for 1 July 20 Allocation

Scenario 1 Scenario 2 Scenario 3 Scenario 4 (Most Likely) Inflows Zero Inflows DoR starting July 2020 Zero Inflows Zero Inflows

Delivery Restricted Unrestricted Restricted Restricted Operations IRG3 – 130 GL IRG3 – 130 GL IRG3 – 130 GL IRG3 – 130 GL S&D, LWU 100% (17 GL) 100% 100% 100% HS 70% (19 GL) 70% 70% 70% GS (CO) 100% of usable remaining CO from 19-20(est. around 29GL) 100% of usable remaining CO from 19-20(est. around 29GL) All usable remaining CO from 2019-20 suspended for use 50% of usable remaining CO from 19-20(est. around 15GL) Inflows that underpins unrestricted delivery

Based on 140 GL

combined inflows in winter/spring 2021

Requires 40GL

combined inflows June to Oct 2020 for unrestricted delivery ECA

WQA

10 10 10 10 Wyangala %

n 30 June

2021 Ceased to flow end March 2021 2.7% Ceased to flow end June 2021 Ceased to flow end May 2021. 2.8% with 40GL inflow

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