Regional water availability report Weekly edition 10 June 2019 waternsw.com.au Contents 1. Overview ................................................................................................................................................. 3 2. System risks ............................................................................................................................................. 3 3. Climatic Conditions ............................................................................................................................... 4 4. Southern valley based operational activities ..................................................................................... 6 4.1 Murray valley .................................................................................................................................................... 6 4.2 Lower Darling valley ........................................................................................................................................ 8 4.3 Murrumbidgee valley .................................................................................................................................... 10 5. Central valley based operational activities ..................................................................................... 14 5.1 Lachlan valley ................................................................................................................................................ 14 5.2 Macquarie valley ........................................................................................................................................... 18 6. Northern valley based operational activities ................................................................................... 22 6.1 Namoi valley ................................................................................................................................................... 22 6.2 Gwydir valley .................................................................................................................................................. 25 6.3 Border rivers ..................................................................................................................................................... 27 6.4 Barwon-Darling River system ........................................................................................................................ 29 7. Coastal valley based operational activities ..................................................................................... 34 7.1 Bega river ........................................................................................................................................................ 34 7.2 Hunter valley ................................................................................................................................................... 35 7.3 Toonumbar Dam ............................................................................................................................................ 37 8. Rural Dam Levels .................................................................................................................................. 38 Water availability weekly report 2 1. Overview WaterNSW manages and operates 42 dams and storages to deliver water for environmental, domestic, town water, stock, industrial and irrigation purposes across the state. WaterNSW storages provide supplies to all the major river systems in Western NSW, Greater Sydney, the Southern Highlands, Shoalhaven Bay as well as the Hunter, Bega, and Iron Pot valleys in coastal NSW. The total active storage percentage of rural water supplies on 10 June 2019 was 29.2% of the total active storage capacity. This was an increase of 0.5% from last week. The total storage level of urban water supplies on 10 June 2019 was 52.9% of the total storage capacity. This was a decrease of 0.2% since last week. 2. System risks • NSW and Commonwealth environmental water releases in the Border and Gwydir valleys for fish habitat maintenance in those valleys is progressing and entering the unregulated Barwon River. A Section 324 temporary water restriction is in place in the Barwon Darling water source to restrict access to this water. • Flows from the Nebine/Culgoa River reached the Darling River upstream of Bourke on 9 May and Bourke Weir has risen about 1.0m. • Flows from the Warrego River have reached the Darling River at Louth and Tilpa. These ongoing flows from the Warrego River are possibly going to contribute a small volume into Lake Wetherell at Menindee. • Menindee Lakes continues to be below the 480/640GL trigger for NSW control, and four temporary block banks have been constructed to extend drought security beyond January 2019. Releases at Weir 32 ceased in mid-February and cease to flow conditions between the banks has now commenced. The cease to flow conditions increase the possibility of decreasing water quality and fish deaths, with increases in; salinity, pH and Algae, and reduced dissolved oxygen. • In the Lower Namoi, releases from Keepit Dam have ceased and until last month’s rain, cease to flow conditions existed from downstream of Keepit Dam to Walgett. Cease to flow has recommenced from Gunnedah to Walgett. • The Peel valley is in drought stage 3 and drought planning is underway, including the potential to restrict flows below Dungowan village to secure town water supply. Water availability weekly report 3 • In the Macquarie the combination of current storage volumes and a continuation of zero inflows will mean that there isn’t enough water to maintain river flows to the whole valley for all of 2019/20. If these zero inflows continue then the priority will be to extend supply for towns and critical industries. This will mean cease to flow is likely to be implemented for the river below Warren and for Duck and Crooked Creeks early in spring. If inflows do not occur at all next year, then all storage water will be depleted before the end of June 2020 and the whole river would then stop flowing. • The Lachlan system continues to experience very low inflows, only slightly above pre-2004 minimums since the last general security allocation in August 2017. If low inflows continue this winter then the system may record new low inflow records and, based on BOM’s recent outlook, this is a real possibility. If a winter recovery does not eventuate restrictions on availability of general security account water may be required in 2019-20 (drought stage 3). • Due to drought conditions, end of system daily environmental flow requirements in the Belubula River are being met intermittently, and customers are regularly advised of rescheduling requirements. 3. Climatic Conditions Figure 1 - Weekly rainfall totals for New South Wales Water availability weekly report 4 This week’s weather forecast For the first part of the week, the entire state should receive 1 – 5 mm of rainfall with the exception of the southern regions which are forecast to receive up to 15mm. As the week progresses a further 1 – 5mm should be seen across the entire state with the exception of the southern western region of the state which is predicted to remain dry. Very mild conditions are forecast to continue across NSW with temperatures ranging from – 3 degrees in the south, to 24 degrees in the North. The Snowy Mountains region again is expected to see below zero conditions for the entire week. Figure 2a – First 4-day Forecast (11 - 14 June 2019) Figure 2b – Following 4-day forecast (15 - 18 June 2019) Below average winter rainfall is likely for much of New South Wales. Figure 3 – 3-month rainfall outlook Water availability weekly report 5 4. Southern valley based operational activities 4.1 Murray valley Storage and release status • Hume Dam is currently 18% of active capacity, releasing about 1280ML/d. • Release downstream of Yarrawonga Weir is about 4,590ML/day and is likely to increase to meet increasing operational needs. • The Edward River Offtake gates are open, and the flow is currently about 790ML/d and will fluctuate with river levels. • The Gulpa Creek Offtake gates are open, and the flow is currently about 216ML/d and is likely to vary in line with the flows in Murray channel. • Stevens Weir level is about 4.14m. Water level upstream of Wakool Canal offtake is about 1.48m. Flow downstream of Stevens Weir has reduced to about 565ML/day and is expected to increase to about 650 ML/d during the week. • Flows in the Colligen Creek (170ML/day) and Yallakool Creek (170ML/day) are both to remain steady during the week, in accordance with June water sharing plan target of 170ML/d at both locations. • No flows at Wakool River offtake (0ML/day). It is expected to revert to 30 ML/d late next week. • Flow in Niemur River at Mallan School is currently about 136ML/d and is likely to increase to about 150 ML/day during this week. • Merran Creek flows upstream of its confluence with Wakool is about 110 ML/day and is likely to decrease over the week. • Flow in Wakool River at Stoney Crossing is currently at about 430 ML/day and is likely to decrease over the week. • Flows at Balranald are currently about 429ML/day and is likely to remain steady in accordance with the June water sharing plan target of 429ML/d. • Lake Victoria is currently holding about 266GL or 28.8% of active capacity. The flow to South Australia is about 2,780ML/d. ( https://riverdata.mdba.gov.au/system-view ) Environmental water operations • Current operational requirements downstream