Operations update

February 2020 rainfall event

Barwon-Darling

22 April 2020 - Update • Menindee inflow forecast is now for 450,000ML to 490,000ML. • Small increase in forecast inflows from the Border . • No significant changes to forecast inflows from the Moonie, Namoi and Gwydir . • Significant flow from recent rainfall and around 23 GL observed at Castlereagh at Gungalman, 13 GL at Marthaguy Creek at Carinda and 5 GL at Bogan at Gongolgon over last 3 days. According to BoM forecast, Bogan flow will peak at Gongolgon early next week. • Geera gauge is back on-line after being out since 14 April 2020. Geera forecast is reduced based on confirmed figures. Forecast volume at Brewarrina has not changed due to observed gain between Geera and Brewarrina. Possibly a rating issue between Geera and Brewarrina. • In the Condamine Balonne over 1,400 GL was observed at St George. Based on observed flow at upstream NSW gauges and BoM’s water level forecast, around 174-177GL inflow is now expected from upstream of Warraweena and around 32-34 GL is expected from Bokhara River upstream of Beemery. • Around 45-50GL inflow is considered at Dick’s Dam as inflow from the , including flows from local rain that commenced on 6 March. Additional Warrego flows are now arriving at Louth from flows that bypass Dick’s Dam. • Forecasts include estimated extractions from Mungindi to Culgoa junction from 27 Feb 2020 and downstream of Culgoa junction from 6 Mar 2020.

Forecast Flows The Barwon-Darling system is an unregulated river system, which travels through a very arid environment with significant losses due to high evaporation and long flow-travel times. It is very difficult to accurately forecast downstream flows as local conditions can vary significantly over the number of weeks it takes the water to travel along the river. The below summaries are the current forecast estimates of flows along the system and assume that the Barwon-Darling temporary water restrictions have been lifted. Unless there is a substantial change to the forecast, the next update will be provided on Monday 27 April 2020.

WaterNSW ABN 21 147 934 787 169 Macquarie Street Parramatta NSW 2150 PO Box 398, Parramatta NSW 2124 T 1300 662 077 E [email protected] waternsw.com.au

Location Observed Total forecast Date of flow Comments about inflows to each volume volume – arrival section (ML) including observed (ML) Mungindi 72,883 77,000 – 79,000 15 Feb 2020 Inflows are from the Presbury 64,845 68,000-71,000 5 Feb 2020 Mogil Mogil 204,846 208,000-211,000 27 Jan 2020 Expected total inflows (observed and forecast) are 17-18 GL from Gil Gil and about 76 GL from Moonie. Gain from localised inflows. Collarenberi 240,714 243,000 – 246,000 6 Feb 2020 Expected total inflows (observed (total flow and forecast) are 25 GL from Mehi. including Old Total observed flows at Garwon Pockataroo (Old Pockataroo) are 10 GL anabranch) Tara 258,633 260,000 – 265,000 7 Feb 2020 Gain from localised inflows Walgett 364,717 368,000 –373,000 9 Feb 2020 Expected total inflows (observed and forecast) are about 91-92 GL from Namoi at Goangra Boorooma 346,582 375,000 – 385,000 13 Feb 2020 Flows were out of bank Geera 416,876 460,000 - 490,000 12 Feb 2020 Significant inflow continuing from and Marthaguy Ck from recent rainfall Brewarrina 363,636 430,000 – 460,000 16 Feb 2020 Beemery 476,258 555,000 – 585,000 18 Feb 2020 Based on observed flows at NSW gauges, around 32-34 GL inflow from Bokhara. Gain from localised inflows. Warraweena 588,194 680,000 – 710,000 19 Feb 2020 Based on observed flows at NSW gauges, around 174-177 GL inflow from Culgoa. Bourke 530,602 598,000 – 640,000 20 Feb 2020 Louth 503,435 595,000 – 625,000 24 Feb 2020 Around 45-50 GL inflow considered as inflow from Warrego Tilpa 473,847 567,000 – 597,000 28 Feb 2020 Wilcannia 465,192 572,000 – 602,000 5 Mar 2020 Lake Wetherell, 370,797 450,000 - 490,000 10 Mar 2020 Around 10-20 GL expected from Lake Tandure Dolo-Bonley Creek system and Lake downstream of Wilcannia. Higher Pamamaroo losses between Wilcannia and Lake Wetherell.

WaterNSW ABN 21 147 934 787 169 Macquarie Street Parramatta NSW 2150 PO Box 398, Parramatta NSW 2124 T 1300 662 077 E [email protected] waternsw.com.au