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River Murray Weekly Report For the week ending Wednesday, 19 August 2020

Trim Ref: D20/33451

Rainfall and inflows There was widespread rain across the majority of the Murray-Darling Basin this week (Map 1). Moderate rain and snow was recorded over the Australian Alps, including 62 mm at Cabramurra (bordering the Basin). Downstream of Hume Dam, Victorian catchments received moderate totals, with Mongan’s Bridge on the Kiewa River recording 24 mm and the Ovens River at Rocky Point recording 32 mm. On the Goulburn River, 21 mm was recorded at Shepparton this week.

Map 1 - Murray-Darling Basin rainfall totals for week ending 19 August 2020 (Source: Bureau of Meteorology)

There were reasonable streamflow responses in the mid-Murray tributaries following the rain this week. Tributary inflows from the Ovens, Kiewa and Goulburn Rivers remain sufficient to meet and exceed downstream flow requirements. The BoM is forecasting further widespread rain across the Murray-Darling Basin for the coming 8 days with totals of between 15 and 50 mm predicted across some areas of the southern connected basin. Further streamflow increases would be expected if the forecast rainfall eventuates.

Specific information about flows at key locations can be found at the MDBA’s River Murray data webpage. Up-to-date river data for sites in the upper Murray can also be found on BoM’s website and in the Murray River Basin Daily River Report at the WaterNSW website.

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The BoM report that the El Niño–Southern Oscillation (ENSO) is currently neutral yet have recently upgraded the ENSO outlook from La Niña WATCH to La Niña ALERT, which indicates that the chance of La Niña forming in 2020 is around 70%. The Indian Ocean Dipole (IOD) is currently neutral yet warmer than average waters are likely in much of the central and eastern Indian Ocean. La Niña and warmer eastern Indian Ocean temperatures typically increase the chance of above average rainfall across much of Australia during spring, which is reflected in the most recent rainfall outlook for September to November 2020 (Map 2).

Map 2 – Wetter conditions are forecast across eastern Australia for September to November 2020 (Source: Bureau of Meteorology)

System operations Unregulated flow event Heavy rainfall in late April soaked catchments and boosted tributary inflows from the Ovens, Kiewa and Goulburn Rivers. Catchments have been responsive since, with healthy tributary inflows continuing during May, June, July and now, into mid-August. These inflows have provided more than enough water to supply system requirements and allowed releases from Hume Dam to be maintained at the minimum release of 600 ML/day since late April.

The tributary inflows have also resulted in the effective filling of Lake Victoria and a period of unregulated flows into South Australia since 27 June. Improved mid-Murray streamflow responses during the last week and associated reduction in losses and demands has meant that there remains sufficient surplus water in the River Murray for the unregulated event to extend further upstream of Lake Victoria, to Yarrawonga until 25 August.

Whilst unregulated flows continue, Lake Victoria will be operated at levels below full supply and in accordance with the Lake Victoria Operating Strategy. This means that if additional rain and upstream tributary inflow results in another extension to unregulated flows, the level may be further reduced to help minimise the impacts of inundation on the vegetation and sensitive cultural heritage material on the lake shore. The lake will be re-filled at the conclusion of the unregulated event. For more information on the expected duration and the river reaches where unregulated flow currently applies, please refer to your local water authority.

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River operations

River operations and the COVID-19 virus The MDBA is continuing to work with government partners and stakeholders during this challenging time. In response to the impact of COVID-19, the MDBA has enacted business continuity arrangements to ensure the continued operation of our business functions. River operations have been identified as a priority in this time as running the river is essential to supporting irrigation supply to agricultural industries.

We hope all our community members remain safe at this time. We encourage all river users to evaluate plans against government advice, physical distancing and travel, and to support actions to limit the spread of COVID-19.

Water quality impacts An amber alert for blue-green algae remains current in the River Murray system upstream of Euston Weir. It is important that water users regularly keep up to date with algal alerts, notices and health warnings. This information is available through Goulburn-Murray Water and WaterNSW.

River operations Over the past week, MDBA total active storage increased by 70 GL to 4,214 GL (50% capacity). Menindee Lakes storage volume remains below 640 GL and is unavailable for MDBA use. Therefore, the total active storage available to the Murray does not include water held in the Menindee Lakes.

At Dartmouth Reservoir (Photo 1), the storage increased by 19 GL this week to 2,088 GL (54% capacity). The release, measured at Colemans, continued to target the minimum flow of 200 ML/day.

Photo 1 – Dartmouth Reservoir at 54% with the high-level tower nearly submerged (Photo courtesy of Peter Liepkalns, GMW)

• Minimum releases from Hume Dam continue as tributary inflows meet downstream requirements • Increased likelihood of La Nina forming in 2020 suggesting wetter conditions for eastern Australia • Inflows from the Goulburn River boost mid-Murray streamflow following rain • Unregulated flow event extended to upstream to Yarrawonga until 25 August

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At Hume Reservoir, downstream tributary inflows from the Ovens, Kiewa and Goulburn Rivers continue to meet Murray demands which has enabled the Hume outflow to be maintained at the minimum release of 600 ML/day. This, combined with reasonable inflows to Hume, due in part to rainfall during the week, has resulted in a 60 GL increase in the storage to 1,634 GL (55% capacity). Hume Reservoir is expected to continue to rise in coming weeks should further forecast rain eventuate.

At Lake Mulwala, the pool level is currently near 124.7 m AHD, which is within the normal operating range between 124.6 and 124.9 m AHD. During the week there was no diversion to Mulwala Canal. The diversion into Yarrawonga Main Channel increased slightly to around 260 ML/day and is expected to remain near this rate. The release from Yarrawonga Weir was gradually increased from 5,800 ML/day at the start of the week to the current release of around 7,000 ML/day to accommodate the streamflow responses from the Ovens and Kiewa Rivers. As rain continues to be forecast, the release is expected to vary over the coming week to manage the weir pool level.

In the Barmah-Millewa Forest this week, forest managers co-ordinated the opening of a number of regulators on behalf of environmental water holders. Opening forest regulators provides connectivity between the river and the floodplain in winter and into spring while river flows are within channel capacity. This action will increase habitat for native fish and improve the transfer of valuable nutrients from the floodplain to the river. These nutrients are the base of a food web that supports the entire river ecosystem including algae, aquatic plants, macroinvertebrates, turtles, fish, platypus and birds.

The gates at Edward and Gulpa Creek offtake regulators are raised clear of the water, allowing inflows to the Edward River to vary with the Murray. Flows through the Edward and Gulpa offtakes are currently near 920 and 260 ML/day, respectively. At Stevens Weir, the downstream flow averaged around 750 ML/day and may increase over the coming week.

Photo 2: A nice spot to sit at Waranga Basin, near Goulburn Weir, at 95% (effectively full) (Photo courtesy Bob Knowles, GMW)

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Back on the River Murray, flow at Barmah averaged around 3,900 ML/day and is expected to gradually rise over the coming week. Inflows from the Broken Creek, measured at Rice’s Weir, increased to average around 300 ML/day this week. Maintenance works in the irrigation district have now finished and water is being delivered from irrigation outfalls on behalf of environmental water holders. The Waranga Basin (Photo 2), near Goulburn Weir, is now effectively full and elevated flows from recent rain was passed through Goulburn Weir to the River Murray.

On the Goulburn River, the flow measured at McCoys Bridge increased from around 3,300 ML/day to the current rate near 5,100 ML/day as streamflow’s responded well to rainfall this week. The flow may increase further over the coming days should rain continue as forecast. Allocation trade from the Goulburn to the Murray system is currently closed. Information regarding opportunities for allocation trade between the Goulburn and Murray Valleys is available at the Victorian water register website.

Diversions to National Channel from the Torrumbarry Weir pool averaged around 780 ML/day this week. The diversion may increase again over the coming week with the irrigation season now commenced, however the continued forecast for rain may postpone the potential rise. The Torrumbarry Weir pool continued to target the Full Supply Level (FSL) of 86.05 m AHD over the past week. This week the release from Torrumbarry Weir gradually increased to a current flow of near 6,500 ML/day and is expected to continue to increase in the coming days as streamflow responses from recent rain move through the system.

Inflow from the Murrumbidgee River, measured at Balranald, averaged just over 1,200 ML/day this week and is anticipated to increase slightly over the coming week. The Murrumbidgee IVT balance is open for trade from the Murray to the Murrumbidgee (99.9 GL) but remains closed to trade from the Murrumbidgee to the Murray. Supplementary access for the Murrumbidgee River and Yanco/Billabong Creek systems was announced this week after significant rain and flow increases were observed along the upper Murrumbidgee and its tributaries. See the WaterNSW website for more information.

At Euston Weir, the weir pool level has been gradually returned to FSL over recent weeks and is expected to reach this level in the coming days. This week the downstream release averaged near 7,200 ML/day and is expected to start to increase over the coming week as higher flows arrive from upstream.

This week the Menindee Lakes storage decreased by 1 GL to 459 GL (27% capacity). The downstream release, measured at Weir 32, decreased slightly to the current rate near 220 ML/day. Despite the rainfall and streamflow responses during recent months, in many parts of NSW drought conditions persist with extensive water restrictions still in place. Links to drought services and assistance can be also accessed via the MDBA drought webpage.

At Wentworth Weir, the weir pool level is being managed to target around FSL (30.80 m AHD) but is expected to vary 10 cm above and below this level as part of normal operations. The downstream flow continued to recede this week from 9,000 ML/day to the current rate near 6,500 ML/day. Flows are expected to remain around this rate for the coming week before increasing again as higher flows reach Wentworth towards the end of August.

The Lock 9 weir pool continues to vary just above FSL. Lock 8 will return to FSL early in the coming week. The Lock 7 weir pool continues to vary near FSL.

After reaching 99% capacity (effectively full) last week, Lake Victoria decreased by 9 GL to 663 GL (98% capacity) this week. As unregulated flows continue in reaches upstream of Lake Victoria, the storage is now being actively drawn down in accordance with the Lake Victoria Operating Strategy. The strategy aims to fill the storage as late as possible while also holding a steady level for as short a time as possible to minimise erosion and inundation impacts on sensitive foreshore vegetation and cultural heritage material.

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Photo 3: Paddle steamer PS Ruby returning to Wentworth after being slipped at Buronga for maintenance (photo courtesy of Jeff Milne)

The flow to South Australia increased sharply late last week to near 12,000 ML/day resulting from a combination of increased flows in the lower Murray and outflows from the drawdown of Lake Victoria. The flow has since decreased back to the current rate near 7,500 ML/day. The current flow remains above August entitlement flow (4,000 ML/day) due in part to ongoing unregulated flows attributed to modest streamflow responses during the last week, and an associated reduction in losses and demands. Flows may decrease somewhat during the coming week but will likely remain at an elevated rate, particularly if further rain and inflow takes place.

The Lower Lakes 5-day average water level remained at 0.80 m AHD. The arrival of unregulated flows to the Lower Lakes allowed over 200 GL to be released to the Murray Mouth and Coorong during July via Tauwitchere, Goolwa, Mundoo, Ewe Island and Boundary Creek Barrages. Increased barrage releases will continue to be made during August when conditions allow to target outcomes in the Coorong. For information on barrage releases and South Australia’s entitlement flow, see the South Australian Department for Environment and Water Weekly River Murray Flow Report.

For media inquiries contact the Media Officer on 02 6279 0141

ANDREW REYNOLDS Executive Director, River Management

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Water in Storage Week ending Wednesday 19 Aug 2020

MDBA Storages Full

Supply Level

Full Supply Volume

Current Storage

Level Current Storage Dead

Storage Active

Storage

Change in Total Storage for the

Week (m AHD) (GL) (m AHD) (GL) % (GL) (GL) (GL)

Dartmouth Reservoir 486.00 3 856 453.93 2 088 54% 71 2 017 +19 Hume Reservoir 192.00 3 005 184.10 1 657 55% 23 1 634 +60 Lake Victoria 27.00 677 26.89 663 98% 100 563 -9 Menindee Lakes 1 731* 459 27% (- -) # 0 -1 Total 9 269 4 867 53% - - 4 214 +70 Total Active MDBA Storage 50% ^ Major State Storages

Burrinjuck Reservoir 1 026 760 74% 3 757 +41 Blowering Reservoir 1 631 1 150 71% 24 1 126 +35 Eildon Reservoir 3 334 1 762 53% 100 1 662 +28

* Menindee surcharge capacity – 2050 GL ** All Data is rounded to nearest GL ** # NSW has sole access to water when the storage falls below 480 GL. MDBA regains access to water when the storage next reaches 640 GL. ^ % of total active MDBA storage

Snowy Mountains Scheme Snowy diversions for week ending 18 Aug 2020 Storage Active Storage (GL) Weekly Change (GL) Diversion (GL) This Week From 1 May 2020 Lake Eucumbene - Total 945 +17 Snowy-Murray +11 405 Snowy-Murray Component 399 +23 Tooma-Tumut +5 90 Target Storage 1 190 Net Diversion 6 314 Murray 1 Release +12 500

Major Diversions from Murray and Lower Darling (GL) * New South Wales This Week From 1 July 2020 Victoria This Week From 1 July 2020 Murray Irrig. Ltd (Net) -0.2 64 Yarrawonga Main Channel (net) 1.6 6 Wakool Sys Allowance 0.6 18 Torrumbarry System + Nyah (net) 0 0 Western Murray Irrigation 0.0 1 Sunraysia Pumped Districts 0.1 3 Licensed Pumps 1.3 23 Licensed pumps - GMW (Nyah+u/s) n/a 1 Lower Darling 0.0 0 Licensed pumps - LMW 1.2 9 TOTAL 1.7 106 TOTAL 2.9 19

* Figures are derived from actual and estimates where data is unavailable. Please note that not all data may have been available at the time of creating this report. ** All data above is rounded to nearest 100 ML for weekly data and nearest GL for cumulative data

Flow to South Australia (GL) * Flow to SA will be greater than normal entitlement for this month due to environmental flows.

Entitlement this month 124.0 * Flow this week 65.7 (9 400 ML/day) Flow so far this month 158.6 Flow last month 358.2

Salinity (EC) (microSiemens/cm at 25o C) Current Average over the last week Average since 1 August 2020 Swan Hill 110 120 120 Euston - - - Red Cliffs 130 130 130 Merbein 130 150 140 Burtundy (Darling) 340 340 340 Lock 9 130 120 120 Lake Victoria 120 120 120 Berri 150 150 140 Waikerie 210 200 190 Morgan 200 190 200 Mannum 240 210 210 Murray Bridge 220 220 240 Milang (Lake Alex.) 910 910 950 Poltalloch (Lake Alex.) 370 370 400 Meningie (Lake Alb.) 1 580 1 660 1 690 Goolwa Barrages 1 290 1 260 1 390

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River Levels and Flows Week ending Wednesday 19 Aug 2020

Minor Flood

Stage Gauge Height Flow Trend Average Flow this Week

Average Flow last Week

River Murray (m) local (m)

(m AHD) (ML/day) (ML/day) (ML/day)

Khancoban - - - 2 540 R 2 640 3 330 Jingellic 4.0 1.99 208.51 7 110 F 7 100 6 170 Tallandoon ( Mitta Mitta River ) 4.2 1.59 218.48 990 R 940 830 Heywoods 5.5 1.39 155.02 600 S 600 600 Doctors Point 5.5 1.64 150.11 1 890 F 2 160 1 920 Albury 4.3 0.79 148.23 - - - - Corowa 4.6 0.82 126.84 2 380 F 2 270 1 930 Yarrawonga Weir (d/s) 6.4 1.20 116.24 7 050 R 6 080 4 660 Tocumwal 6.4 1.60 105.44 5 800 R 5 330 4 090 Torrumbarry Weir (d/s) 7.3 2.25 80.80 6 440 R 6 070 3 880 Swan Hill 4.5 1.32 64.24 6 780 R 5 230 4 970 Wakool Junction 8.8 2.79 51.91 7 200 R 6 310 7 650 Euston Weir (d/s) 9.1 1.36 43.20 7 200 R 7 180 9 750 Mildura Weir (d/s) - - 7 140 F 7 720 10 390 Wentworth Weir (d/s) 7.3 2.96 27.72 6 470 F 7 500 9 910 Rufus Junction - 3.57 20.50 7 170 R 9 020 5 770 Blanchetown (Lock 1 d/s) - 0.91 - 8 770 F 8 750 6 850 Tributaries Kiewa at Bandiana 2.8 1.72 154.95 1 510 F 1 640 1 540 Ovens at Wangaratta 11.9 9.04 146.72 3 580 F 3 350 2 700 Goulburn at McCoys Bridge 9.0 3.59 95.01 5 100 R 3 580 1 680 Edward at Stevens Weir (d/s) 5.5 0.90 80.67 600 F 750 660 Edward at Liewah - 1.60 56.98 940 F 960 870 Wakool at Stoney Crossing - 1.46 54.95 570 F 590 580 Murrumbidgee at Balranald 5.0 1.65 57.61 1 220 R 1 240 1 130 Barwon at Mungindi 6.1 3.27 - 210 F 150 120 Darling at Bourke 9.0 4.22 - 1 020 R 910 570 Darling at Burtundy Rocks - 0.72 - 170 F 170 170 Natural Inflow to Hume 11 120 8 320

(i.e. Pre Dartmouth & Snowy Mountains scheme)

Weirs and Locks Pool levels above or below Full Supply Level (FSL) Murray FSL (m AHD) u/s d/s FSL (m AHD) u/s d/s Yarrawonga 124.90 -0.19 - No. 7 Rufus River 22.10 +0.04 +1.26 No. 26 Torrumbarry 86.05 +0.00 - No. 6 Murtho 19.25 +0.07 +0.24 No. 15 Euston 47.60 -0.02 - No. 5 Renmark 16.30 +0.14 +0.46 No. 11 Mildura 34.40 +0.00 +0.17 No. 4 Bookpurnong 13.20 +0.25 +0.93 No. 10 Wentworth 30.80 -0.02 +0.32 No. 3 Overland Corner 9.80 +0.03 +0.60 No. 9 Kulnine 27.40 +0.00 +0.04 No. 2 Waikerie 6.10 +0.17 +0.52 No. 8 Wangumma 24.60 -0.03 +0.14 No. 1 Blanchetown 3.20 +0.16 +0.16

Lower Lakes FSL = 0.75 m AHD Lake Alexandrina average level for the past 5 days (m AHD) 0.80

Barrages Fishways at Barrages Openings Level (m AHD) No. Open Rock Ramp Vertical Slot 1 Vertical Slot 2 Dual Vertical Slots Goolwa 128 openings 0.67 3 - Open Open - Mundoo 26 openings 0.58 1 - - - Open Hunters Creek - - - - Open - - Boundary Creek 6 openings - 1 - Open - - Ewe Island 111 gates - All closed - - - Open Tauwitchere 322 gates 0.62 5 Open Closed Open -

AHD = Level relative to Australian Height Datum, i.e. height above sea level

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Week ending Wednesday 19 Aug 2020

State Allocations (as at 19 Aug 2020)

NSW - Murray Valley Victorian - Murray Valley High security 97% General security 8%

High reliability 24% Low reliability 0%

NSW – Murrumbidgee Valley

Victorian - Goulburn Valley High security 95% General security 32%

High reliability 40% Low reliability 0%

NSW - Lower Darling

South Australia – Murray Valley High security 100% General security 30%

High security 100%

NSW : https://www.industry.nsw.gov.au/water/allocations-availability/allocations/summary

VIC : http://nvrm.net.au/seasonal-determinations/current

SA : https://www.environment.sa.gov.au/topics/river-murray/water-allocations-and-announcements