Lachlan River Operations 2019- 20 River Operations Stakeholder Consultation Committee (ROSCCo) 19 May 2020 1
Recent Rainfall 1 Feb to 30 Apr WaterNSW 2
Recent rain hydrographs 76,000 ML 44,000 ML WaterNSW 3
Recent rain hydrographs 17,000 ML 13,000 ML 2,500 ML 2,500 ML WaterNSW 4
Recent rain hydrographs WaterNSW 5
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% 6
Flows in ML/d 1000 1500 2000 2500 3000 3500 4000 500 0 01-Jul-19 Wyangala Dam Operations 11-Jul-19 Dam Inflows (Monthly) 21-Jul-19 31-Jul-19 10-Aug-19 20-Aug-19 30-Aug-19 09-Sep-19 19-Sep-19 Dam Release 29-Sep-19 Lachlan River Operation 2019-20 'spring pulse' 09-Oct-19 19-Oct-19 29-Oct-19 08-Nov-19 Extractive Orders_Upper Lachlan 18-Nov-19 28-Nov-19 08-Dec-19 Lake C and Brewster WR To maintain levels in 18-Dec-19 28-Dec-19 07-Jan-20 17-Jan-20 27-Jan-20 06-Feb-20 Dam Level 16-Feb-20 26-Feb-20 07-Mar-20 17-Mar-20 27-Mar-20 06-Apr-20 0% 20% 40% Dam Level in % 7
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) 8
Extreme event stages Stage Water quantity Water quality Raw water can be treated Stage 1 Continue to deliver water as normal with usual methods Normal management Operational surface water measures to conserve supplies Minor adjustments to treat Stage 2 raw water Emerging water shortage Potential or actual impacts on groundwater Restrictions on water for: Major adjustments are Stage 3 High priority licences ∙ needed to treat raw water General security licences ∙ Severe water shortage Unacceptable groundwater impacts Water only available for critical human Not possible to treat raw needs water with standard processes Stage 4 Restrictions on all licences Critical water shortage Raw water likely to remain Risk to long term availability of the untreatable over the longer groundwater resources term 9
Water Account Summary Sum of Sum of Sum of Sum of Sum of Sum of Allocation Allocation Share Account Available Sum of Carryover Assignments Assignments Sum of 30 April 20 Component Balance Water AWD Vol In In Out Usage - DOMESTIC AND STOCK 10,954 7,273 7,170 10,949 12 8 8 3,669 DOMESTIC AND STOCK [DOMESTIC] 176 173 173 176 - - - 3 DOMESTIC AND STOCK - [STOCK] 1,599 1,407 1,407 1,599 2 - - 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 12 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 10
End April 2020 assessment 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) 14.7% • 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 WaterNSW 11
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 12
River Operations Under IRG 3 13
What Does it take to operate Lachlan River - Transmission and Operation Loss IRG stage 3 IRG stage 4 Millennium Drought Regulated Lachlan River Typical dry drought drought Transmission & Operations Losses year (GL) 2004-05 2006-07 2008-09 operations operations Main regulated river from dam to Lake 56 27 76 59 55 55 Cargelligo Weir Wallamundry/Wallaroi/Nerrathong 14 14 13 12 12 6 system 12 7 7 6 6 3 Replenishment flows into Booberoi Ck Flows to Lake Cargelligo through 5 3 3 3 3 emergency works for TWS & BLR 15 4 2 0 2 2 Losses in regulated Willandra Ck system 40 42 47 40 39 20 Losses LC Weir to Booligal 13 15 15 14 13 6 Target Flows required below Booligal Replenishment Flows into Willandra 9 5 0 0 0 0 Creek Replenishment Flows into Merrowie 9 0 0 0 0 0 Creek Replenishment Flows into 7 0 0 0 0 0 Merrimajeel/Muggabh Creek 5 0 0 0 0 0 Operational Surplus WaterNSW 14 180 118 163 135 130 95 Total
Resource Availability/Distribution end of April 2020 WaterNSW 15
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 16
Combined inflows to deliver 29 GL GS & begin to ease drought account 17
AWDs during millennium drought in % Year HS LWU S&D GS 2004-05 30 50 30 0 2005-06 100 100 100 19 2006-07 30 80 80 0 2007-08 30 70 50 0 2008-09 30 70 50 0 2009-10 10 50 15 0 18
Discussions and Recommendations • Potential for triggering of translucent flows during drought contingency operations • Relative water availability for HS and GS under drought contingency measures – should HS AWD be lower than 70% to allow access to more of 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 19
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 20
Climate Outlook 21
Wyangala Dam Raising 22
Wyangala Dam Raising For more info visit WaterNSW website: https://www.waternsw.com.au/projects/new-dams-for-nsw/wyangala-dam 23
To keep updated 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 WaterNSW 24
Thank you for joining us today 25 WaterNSW WaterNSW
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End January 2020 assessment 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 4.2% March 2020 1.6% 28 WaterNSW
End January 2020 assessment with February inflows WaterNSW 29
Wyangala Dam Behaviour during Millennium Drought 2003-2010 Wyangala Dam Storage Volume During Millennium Drought 2003 - 2010 450000 45% Wyangala Volume (ML) Wyangala Level (%) 400000 40% 350000 35% 300000 30% 250000 25% 200000 20% 150000 15% 100000 10% 50000 5% 0 0% 01-Jul-03 01-Jul-04 01-Jul-05 01-Jul-06 01-Jul-07 01-Jul-08 01-Jul-09 01-Jul-10 WaterNSW 30
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