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River Murray Weekly Report For the week ending Wednesday, 5 August 2020

Trim Ref: D20/30940

July 2020 summary The Bureau of Meteorology (BoM) reports that, for Australia as a whole, mean maximum temperatures in July 2020 were the seventh-warmest on record. For the Murray-Darling Basin, mean maximum temperatures ranged between near average to very much above average (Map 1). Of particular note were the cooler mean minimum temperatures observed in South Australia and western parts of Victoria and New South Wales, where some locations recorded their lowest July mean minimum temperatures in over 20 years (Map 2).

Map 1 & 2 – Maximum and minimum July 2020 temperature deciles for Australia. Source: Bureau of Meteorology.

The BoM also reports that area-averaged rainfall for the Murray-Darling Basin was 32 per cent below the long-term July average. While much of the northern Basin recorded close to near average rainfall, southern Basin rainfall was generally below average to very much below average with some locations recording their lowest July rainfall on record (Map 3).

Map 3 & 4 – Murray-Darling Basin rainfall deciles and rainfall for July 2020. Source: Bureau of Meteorology.

Given the dry conditions across most of the upper Murray catchment, River Murray System inflows fell below the historical July median. System inflows (excluding environmental, IVT, Darling and Snowy scheme contributions) totalled around 740 GL, which is 56% AEP (annual exceedance probability).

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Weekly rainfall and inflows There was only light rainfall across the southern Murray-Darling Basin this week, predominantly across the Victorian ranges where Taggerty recorded 11 mm (Map 5).

Streamflows in the upper and mid-Murray tributaries continued to recede this week, although tributary inflows from the Ovens, Kiewa and Goulburn Rivers remained sufficient to meet downstream flow requirements. The BoM is forecasting widespread rain across the entire Murray-Darling Basin for the coming 8 days (Map 6). Streamflow increases in many locations are 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.

Map 5 & 6 - Murray-Darling Basin rainfall totals for week ending 5 August & 8 day rainfall forecast as at 6 Aug (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 elevated inflows continuing during May, June and into July. These inflows have been surplus to River Murray 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 provided higher flows along the Murray and with sufficient surplus flow remaining after ensuring the filling of Lake Victoria, a period of unregulated flow commenced on 27 June. Since the start of May, in excess of 360 GL of resource has been captured in Lake Victoria. Over the last week, as tributary inflows and flows along the mid-Murray receded, Lake Victoria has been steered towards full supply and is currently at 95% capacity. Without further rain and inflows (noting rain is forecast) the current period of unregulated flows may cease in the coming week. 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, social 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 at Buronga. 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 (Dartmouth, Hume and Lake Victoria) increased by 79 GL to 4,044 GL (48% capacity) (Figure 1).

Figure 1: MDBA active storage since June 2000.

• Minimum releases from Hume Dam continue as tributary inflows meet downstream requirements

• Flows along mid-Murray receding

• Torrumbarry, Euston & Lock 8 weir pools returning to Full Supply Level

• Lake Victoria approaching Full Supply Level

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At Dartmouth Reservoir, hydroelectricity generation delivered a Dartmouth release, measured at Colemans, of near 1,000 ML/day for most of the week before reducing back to the minimum flow of 200 ML/day. As a result of the higher release and lack of rainfall, the storage decreased by 3 GL this week to 2,051 GL (53% capacity).

At Hume Reservoir, downstream tributary inflows from the Ovens, Kiewa and Goulburn Rivers continue to meet Murray demands which has enabled the Hume release to be maintained at the minimum release of 600 ML/day. This, combined with reasonable inflows to Hume, due in part to the ongoing release of water from Snowy Hydro into the upper Murray, has helped the Hume storage surpass 50%. Over the past week the storage increased by 66 GL to 1,542 GL (51% capacity) and is expected to continue to rise in coming weeks.

Photo 1: Kiewa River – west branch. Photo courtesy Hugo Bowman, MDBA.

At Lake Mulwala, the pool level is currently near 124.8 m AHD, which is within the normal operating range between 124.6 and 124.9 m AHD. During the week diversion to Mulwala Canal briefly increased to 900 ML/day to meet Wakool Main Canal demands before lowering to near 200 ML/day, which is also the current diversion into Yarrawonga Main Channel. The release from Yarrawonga Weir was maintained near 4,000 ML/day and over the coming week the release may increase if forecast rain delivers streamflow responses in the Ovens and Kiewa Rivers.

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 760 and 180 ML/day, respectively. At Stevens Weir, the downstream flow averaged around 650 ML/day and may ease over the coming week.

Back on the River Murray, the flow at Barmah has slowly receded to 3,100 ML/day. Inflows from the Broken Creek, measured at Rice’s Weir, averaged around 30 ML/day this week.

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On the Goulburn River, the flow measured at McCoys Bridge reduced from over 5,000 ML/day to around 1,600 ML/day during the week and is expected to ease further over the coming days. 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 targeted 1,500 ML/day this week, largely to top up storage levels in the mid-Murray lakes. Over the past couple of months the Torrumbarry Weir pool has been varied between 20-30 cm below Full Supply Level (FSL) as part of the weir pool variability program. Varying pool levels assists with reducing the incidence of notching and can help improve bank stability for riverbanks within the influence of the weir pool. The pool is now 14 cm below Full Supply Level (FSL) and is gradually being returned to FSL over the coming week for the commencement of the Victorian gravity irrigation season. This week the release from Torrumbarry Weir reduced from near 9,000 ML/day to 4,200 ML/day and further reduction is expected in the coming days as Goulburn inflows ease further.

Inflow from the Murrumbidgee River, measured at Balranald, averaged around 830 ML/day this week and is anticipated to increase towards 1,100 ML/day 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.

Photo 2: The Tumut River at Tumut, part of the Murrumbidgee catchment. Photo courtesy Kate Sandles, MDBA.

At Euston Weir, the weir pool level is gradually being returned to FSL over the coming fortnight. After the

downstream release peaked near 15,500 ML/day in the previous week, this week the release reduced to

10,500 ML/day and may fall towards 5,000 ML/day over the coming fortnight.

This week the Menindee Lakes storage decreased by 4 GL to 461 GL (27% capacity). The downstream release, measured at Weir 32, averaged around 240 ML/day over the past week. 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.

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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 reduced from a peak

near 14,700 ML/day to 11,500 ML/day and will reduce further over the coming fortnight.

The Lock 9 weir pool continues to vary around FSL. Lock 8 has been targeting 60 cm below FSL until this week. The

level is now 50 cm below FSL and will gradually increase towards FSL over the coming fortnight. The Lock 7 weir

pool continues to vary near FSL.

As tributary inflows and flows along the mid-Murray recede, this week operations recommenced the filling of Lake

Victoria to fill the storage by the conclusion of unregulated flows. The storage increased by 16 GL to 645 GL

(95% capacity) and will continue to approach full supply over the coming week. Should forecast rainfall lead to

renewed inflows, it is possible that Lake Victoria may be actively drawn down in the coming weeks 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.

The flow to South Australia reduced from over 13,000 ML/day to the current flow near 6,900 ML/day and flows will recede further during the coming week as upstream flows subside and additional water is captured in Lake Victoria. The current flow remains above July entitlement (3,500 ML/day) due to ongoing unregulated flows.

The Lower Lakes 5-day average water level is currently 0.81 m AHD. The arrival of unregulated flows to the Lower Lakes has allowed around 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 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 05 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 3 856 453.10 2 051 53% 71 1 980 -3

Hume Reservoir 192.00 3 005 183.27 1 542 51% 23 1 519 +66

Lake Victoria 27.00 677 26.74 645 95% 100 545 +16

Menindee Lakes 1 731* 461 27% (- -) # 0 -4

Total 9 269 4 699 51% - - 4 044 +75

Total Active MDBA Storage 48% ^

Major State Storages

Burrinjuck Reservoir 1 026 485 47% 3 482 +23

Blowering Reservoir 1 631 1 077 66% 24 1 053 +42

Eildon Reservoir 3 334 1 719 52% 100 1 619 +5

* 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 04 Aug 2020

Storage Active Storage (GL) Weekly Change (GL) Diversion (GL) This Week From 1 May 2020

Lake Eucumbene - Total 922 +5 Snowy-Murray +19 379

Snowy-Murray Component 372 +6 Tooma-Tumut +3 83

Target Storage 1 190 Net Diversion 16 296

Murray 1 Release +23 470

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) 4.9 64 Yarrawonga Main Channel (net) 1.5 3

Wakool Sys Allowance 2.4 15 Torrumbarry System + Nyah (net) 0 0

Western Murray Irrigation 0.1 0 Sunraysia Pumped Districts 0.7 3

Licensed Pumps 2.8 23 Licensed pumps - GMW (Nyah+u/s) 0.2 1

Lower Darling 0.0 0 Licensed pumps - LMW 1.8 7

TOTAL 10.2 102 TOTAL 4.2 14

* 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 unregulated flows.

Entitlement this month 124.0 *

Flow this week 74.7 (10 700 ML/day)

Flow so far this month 49.7 Flow last month 356.7

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 120 120 120

Merbein 120 120 120

Burtundy (Darling) 350 340 340

Lock 9 120 120 120

Lake Victoria 120 120 120

Berri 130 130 130

Waikerie 190 220 210

Morgan 230 240 240

Mannum 220 240 240

Murray Bridge 270 270 270

Milang (Lake Alex.) 940 950 950

Poltalloch (Lake Alex.) 440 440 410

Meningie (Lake Alb.) 1 740 1 740 1 740

Goolwa Barrages 1 380 1 560 1 460

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River Levels and Flows Week ending Wednesday 05 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 - - - 3 500 F 3 890 5 730

Jingellic 4.0 1.95 208.47 6 730 F 9 620 11 550

Tallandoon (Mitta Mitta River) 4.2 1.55 218.44 880 F 1 460 1 710

Heywoods 5.5 1.40 155.03 600 S 600 600

Doctors Point 5.5 1.52 149.99 1 510 S 1 700 2 220

Albury 4.3 0.71 148.15 - - - -

Corowa 4.6 0.55 126.57 1 550 F 1 810 2 300

Yarrawonga Weir (d/s) 6.4 0.74 115.78 4 050 S 4 020 4 820

Tocumwal 6.4 1.22 105.06 3 710 F 3 790 5 410

Torrumbarry Weir (d/s) 7.3 1.63 80.17 4 230 F 6 490 10 050

Swan Hill 4.5 1.37 64.29 7 180 F 8 560 12 370

Wakool Junction 8.8 3.30 52.42 9 490 F 10 510 14 040

Euston Weir (d/s) 9.1 1.86 43.70 10 580 F 12 560 15 340

Mildura Weir (d/s) - - 13 070 F 14 290 14 860

Wentworth Weir (d/s) 7.3 3.24 28.00 11 510 F 13 690 14 390

Rufus Junction - 3.46 20.39 6 500 F 10 240 12 650

Blanchetown (Lock 1 d/s) - 0.95 - 9 870 F 11 050 12 900

Tributaries

Kiewa at Bandiana 2.8 1.44 154.67 1 070 F 1 290 1 730

Ovens at Wangaratta 11.9 8.71 146.39 2 490 F 2 790 3 870

Goulburn at McCoys Bridge 9.0 1.85 93.27 1 600 F 3 080 4 490

Edward at Stevens Weir (d/s) 5.5 1.14 80.91 860 F 660 700

Edward at Liewah - 1.50 56.88 860 R 720 680

Wakool at Stoney Crossing - 1.42 54.91 480 F 490 540

Murrumbidgee at Balranald 5.0 1.33 57.29 920 R 830 1 130

Barwon at Mungindi 6.1 3.18 - 110 F 120 130

Darling at Bourke 9.0 4.11 - 530 F 390 60

Darling at Burtundy Rocks - 0.71 - 160 R 160 160

Natural Inflow to Hume 4 880 8 880

(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 -0.11 - No. 7 Rufus River 22.10 -0.00 +1.16

No. 26 Torrumbarry 86.05 -0.14 - No. 6 Murtho 19.25 +0.13 +0.31

No. 15 Euston 47.60 -0.24 - No. 5 Renmark 16.30 +0.18 +0.50

No. 11 Mildura 34.40 -0.06 +0.43 No. 4 Bookpurnong 13.20 +0.31 +0.93

No. 10 Wentworth 30.80 +0.02 +0.60 No. 3 Overland Corner 9.80 +0.03 +0.55

No. 9 Kulnine 27.40 +0.06 -0.35 No. 2 Waikerie 6.10 -2.21 +0.54

No. 8 Wangumma 24.60 -0.50 +0.19 No. 1 Blanchetown 3.20 +0.17 +0.20

Lower Lakes FSL = 0.75 m AHD

Lake Alexandrina average level for the past 5 days (m AHD) 0.81

Barrages Fishways at Barrages

Openings Level (m AHD) No. Open Rock Ramp Vertical Slot 1 Vertical Slot 2 Dual Vertical Slots

Goolwa 128 openings 0.83 4 - Open Open -

Mundoo 26 openings 0.78 2 - - - Open

Hunters Creek - - - - Open - -

Boundary Creek 6 openings - 1 - Open - -

Ewe Island 111 gates - 2 - - - Open

Tauwitchere 322 gates 0.82 12 Open Open Open -

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

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Week ending Wednesday 05 Aug 2020

State Allocations (as at 05 Aug 2020)

NSW - Murray Valley Victorian - Murray Valley

High security 97%

General security 3%

High reliability 19%

Low reliability 0%

NSW – Murrumbidgee Valley

Victorian - Goulburn Valley

High security 95%

General security 16%

High reliability 37%

Low reliability 0%

NSW - Lower Darling

South Australia – Murray Valley

High security 100%

General security 30%

High security 81%

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