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River Murray Weekly Report For the week ending Wednesday, 2 September 2020

Trim Ref: D20/36530

Winter 2020 Summary The Bureau of Meteorology (BoM) reports that winter 2020 was the sixth-warmest on record for Australia, with the mean temperature 1.15 °C above average. The national mean maximum temperature was the third warmest on record for August and 1.60 °C above average, while the mean minimum temperature was 0.70 °C warmer than average. The mean maximum temperatures for the Murray-Darling Basin were generally average to warmer than average while the minimum temperatures were cooler than average in the south and west, trending to warmer than average in the east (Map 1 & 2).

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

Following above average rainfall in autumn 2020, rainfall in winter was below average across much of Victoria, South Australia and Queensland within the catchment of the Murray-Darling Basin (Map 3). In New South Wales (NSW) rainfall was generally closer to average, although the far south west and north east recorded below average rainfall. In contrast, rainfall in the south east of NSW (including the upper Murrumbidgee and Lachlan catchments) was above average.

River Murray system inflows (excluding environmental, IVT, Darling and Snowy scheme contributions) during winter

2020 were 2,090 GL (60% annual exceedance probability (AEP)). This is in the driest 40 % of winter inflows in

124 years of record. Inflows over winter benefited significantly from the wetting up of catchments in autumn.

Above average rainfall in autumn resulted in inflows during May 2020 in the wettest 10% of May inflows on record

(10% AEP). Below average rainfall over winter resulted in relatively lower inflows, with inflows of 32% AEP in June,

56% AEP in July and 73% AEP in August (ie inflows during August 2020 were in the lowest 27% of August inflows on

record).

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a Map 3 - Murray-Darling Basin rainfall deciles for winter 2020. (Source: Bureau of Meteorology)

Inflows from tributaries downstream of Hume Dam have met and exceeded system demands during winter 2020

and resulted in around 380 GL of unregulated flow to South Australia. During this period releases from Hume Dam

have remained at the minimum release rate of 600 ML/d. By comparison, for the same period in 2019-20, an

additional 220 GL above the minimum target was released to meet system requirements (Figure 1).

Figure 1 – Releases from Hume dam during winter 2019 and winter 2020

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With Hume releases at the minimum rate over winter in 2020, the volume stored in Hume continued to build to

around 60% capacity by the end of winter. This compares with the peak capacity of 44% reached at the end of

August in the 2019-20 water year (Figure 2).

Figure 2 –Hume storage for the period 1 June 2019 to 31 August 2020

Considering BoM’s outlook for spring (Map 4), it is likely that the volume stored in Hume will continue to rise over

coming months. However, if drier conditions do eventuate, it is possible that higher releases due to increasing

irrigation demands, the delivery of environmental water and bulk transfers to Lake Victoria may mean the rate of

filling at Hume storage slows or the volume in storage even begins to fall over the coming months. The MDBA has

prepared an outlook which explores potential operating strategies under a range of possible climatic conditions

ranging from very dry to very wet for the 2020-21 water year. This ‘River Murray System Annual Operating Outlook

for 2020-21’ is available on the MDBA website.

Map 4 – Chance of exceeding median rainfall during spring across Australia. Source: Bureau of Meteorology

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August 2020 Summary The BoM reports that, for Australia as a whole, the mean temperature in August 2020 was the sixth-warmest on record and 1.38°C warmer than average. In contrast to this, the mean maximum and minimum temperatures for the Murray-Darling Basin, were generally closer to average or even cooler than average at some locations (Map 5 & 6).

Map 5 & 6 – Maximum and minimum August 2020 temperature deciles for Australia. Source: Bureau of Meteorology.

The BoM also reports that the August area-averaged rainfall total for the Murray-Darling Basin ranked equal 89th highest out of 121 years of record and was 8 per cent above the long-term August mean. In particular, large areas of NSW recorded above average rainfall with some areas recording their highest August rainfall on record (Map 7). In contrast, a large part of the upper Murray catchment within Victoria recorded below average rainfall in August.

Map 7 - Murray-Darling Basin rainfall deciles for August 2020. (Source: Bureau of Meteorology)

River Murray system inflows (excluding environmental, IVT, Darling and Snowy scheme contributions) for August 2020 totalled around 710 GL. This is within the lowest 27% of August inflows on record.

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Rainfall and inflows Conditions were mostly dry across the Murray-Darling Basin this week, with rainfall limited to the southern slopes and ranges (Map 8). The highest totals included 15 mm at Mount William in the Wimmera and Mount Buller AWS in the upper northeast of Victoria. The BoM is currently forecasting a small amount of rainfall over the southern Murray-Darling Basin in the coming 8 days.

Map 8 - Murray-Darling Basin rainfall totals for week ending 2 September 2020 (Source: Bureau of Meteorology)

Flows in the upper Murray tributaries gradually receded this week. 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.

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 August. Theses tributary inflows have resulted in the effective filling of Lake Victoria and an extended period of unregulated flows into South Australia since 27 June.

Dry conditions over the past week and a drier outlook for the coming week has meant access to unregulated flows in reaches upstream of Barmah on the Murray and Stevens Weir on the Edward River have ceased. Further downstream, unregulated flows have been announced until the 5 September and are likely to be extended in the lower reaches.

Whilst unregulated flows continue, Lake Victoria will be operated at levels below full supply and in accordance with the Lake Victoria Operating Strategy to help minimise the impacts of inundation on the vegetation and sensitive cultural heritage material on the lake shore. However, without further rain it is likely the lake will commence filling in the coming week and 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 89 GL to 4,454 GL (53% capacity). The Menindee Lakes storage volume remains below 640 GL and so there is no water currently available to meet Murray system requirements. Therefore, the total active storage available to the Murray does not include water held in the Menindee Lakes. The current MDBA active storage volume is around 500 GL more than for the same time last year, but around 2,000 GL less than the long-term average for the start of September (Figure 3).

Figure 3: MDBA active storage since June 2000.

• MDBA active storage continues to rise

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

• Lock 11 at Mildura closed to boat traffic for maintenance on 15, 16 and 17 of September 2020

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At Dartmouth Reservoir, the storage increased by 16 GL this week to 2,125 GL (55% capacity). The release, measured at Colemans, continued to target the minimum flow of 200 ML/d.

At Hume Reservoir the storage level rose by 80 GL to 1,877 GL (62% capacity). Downstream of Hume, tributary inflows continue to meet Murray demands which has enabled the Hume release to remain at the minimum release of 600 ML/d.

Photo 1: Release from Hume Dam targeting the minimum flow rate of 600 ML/d (photo courtesy Craig Hardge, MDBA)

Photo 2: River Murray downstream of Hume Dam at the Heywoods gauge site whilst release from Hume is targeting 600 ML/d. Note the extent of the ribbon weed in the river channel which grows as water temperatures increase and river levels rise during the warmer months and dies back as water temperatures cool and river levels recede over the cooler months. This makes measuring flow in this reach of the Murray challenging (photo courtesy Mathew Dixon, WaterNSW).

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At Lake Mulwala, the diversion to Mulwala Canal reached 4,300 ML/d as irrigators within the MIL system accessed supplementary water. However with access to supplementary water now ceased for this reach of the river, the diversion has reduced to around 600 ML/d. The diversion into Yarrawonga Main Channel is currently around 300 ML/d and is expected to remain near this rate over the coming week.

The release from Yarrawonga Weir reduced from the peak of 10,100 ML/d to 5,100 ML/d over the week as inflows to the weir from upstream tributaries were diverted and gradually receded. In contrast, the estimated natural peak flow downstream of Yarrawonga (ie if inflows from tributaries in the upper Murray catchments had not been stored in dams or diverted) following the rain last week would have exceeded 30,000 ML/d.

Figure 4: Estimated natural flow downstream of Yarrawonga weir (ie without river-regulation) compared with the actual release

(generated by inflows from the Kiewa and Ovens Rivers). Note the release from Hume Dam is currently at the minimum rate and no

water is being released for irrigation or on behalf of environmental water holders).

Downstream of Yarrawonga Weir, some regulators in Barmah-Millewa Forest are open providing connectivity between the river and the floodplain while river flows are within channel capacity. This action is being undertaken on behalf of environmental water holders and aims to increase habitat for native fish and improve the transfer of valuable nutrients from the floodplain to the river during spring. 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. Forest regulators are anticipated to remain open as part of this action until at least the end of October.

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On the Edward River, return flows from the Murray via the Millewa Forest increased by around 400 ML/day late in the week. These return flows are expected to ease over the coming week back to around 250 ML/d. Diversions into the Wakool River, Yallakool and Colligen Creeks remained at levels sufficient to provide entitlement holders with access to supplementary water. At Stevens Weir, diversions to the Wakool Main Canal reached around 650 ML/d and the release downstream of the weir increased to 1,200 ML/d.

On the Goulburn River, the flow measured at McCoys Bridge peaked at 12,200 ML/d and is now receding. With no significant rainfall forecast in BoM’s current 8 day outlook, inflow to the Murray from the Goulburn is expected to continue to reduce. 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 are targeting 1,000 ML/d. A portion of this diversion is being used to maintain baseflows in the Gunbower Creek with the aim of providing increased habitat for native fish and other aquatic animals over the spring period. Flow in Gunbower Creek returns to the River Murray via Koondrook Spillway, downstream of Torrumbarry Weir near Barham. At Torrumbarry Weir, the release downstream peaked near 16,200 ML/d in response to inflows from the Goulburn River.

Inflow from the Murrumbidgee River, measured at Balranald, remains above the end of system target in response to rainfall in the upper Murrumbidgee catchment in August. Whilst the flow upstream on the Murrumbidgee River at Wagga Wagga has averaged 10,000 ML/d during August, diversions during supplementary access have resulted in the flow at Balranald remaining below 2,500 ML/d to date. Supplementary access for the Murrumbidgee River and Yanco/Billabong Creek systems was extended this week. See the WaterNSW website for more information. 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.

At Euston Weir, the weir pool level is at FSL. The downstream release averaged around 10,600 ML/d and is forecast

to rise above 16,000 ML/d over the coming week.

At Mildura Weir, Lock 11 will be closed to boat traffic on 15, 16 and 17 of September 2020. This is to allow

installation and load testing of the upgraded lock bridge.

Menindee Lakes storage increased by 1 GL to 458 GL (26% capacity). Continuing inflow from a small flow pulse has arrested the slow decline in storage and is now maintaining the volume relatively steady. The downstream release, measured at Weir 32, averaged 240 ML/d. Following the rainfall and streamflow responses during recent months, water restrictions have been lifted in many locations across NSW. Links to drought services and assistance can be accessed via the MDBA drought webpage.

At Wentworth Weir, the weir pool level is being managed to target around FSL. The downstream flow continued to

rise this week and is currently at 9,200 ML/d.

The Lock 9, Lock 8 and Lock 7 weir pools continue to vary near FSL, within their normal operating range.

The storage level at Lake Victoria decreased by 6 GL to 646 GL (95% capacity) this week. The storage level in Lake

Victoria will continue to be managed over the coming weeks in accordance with the Lake Victoria Operating

Strategy. The strategy aims to fill the storage as late as possible while also minimising the length of time the storage

is held at a steady level. This is done with the aim of minimising erosion and inundation impacts on sensitive

foreshore vegetation and cultural heritage material.

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Photo 3: Echidna at Lindsay Island near Lock 7 (photo courtesy David Wood, Mallee CMA )

The flow to South Australia reduced over the past week to around 8,800 ML/d. as unregulated flows continued

across the border. Flow to South Australia will remain above normal Entitlement (4,500 ML/d) into September as

high unregulated flows continue to arrive from upstream.

The Lower Lakes 5-day average water level was 0.82 m AHD. Continuing unregulated flow into the Lower Lakes has allowed around 75 GL to be released to the Coorong this week targeting outcomes in the Coorong and at the Murray Mouth. Increased barrage releases will continue to be made when conditions allow to push fresh water into 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 02 Sep 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 3 856 454.75 2 125 55% 71 2 054 +16

Hume Reservoir 192.00 3 005 185.61 1 877 62% 23 1 854 +80

Lake Victoria 27.00 677 26.75 646 95% 100 546 -6

Menindee Lakes 1 731* 458 26% (- -) # 0 +1

Total 9 269 5 106 55% - - 4 454 +90

Total Active MDBA Storage 53% ^

Major State Storages

Burrinjuck Reservoir 1 026 850 83% 3 847 +4

Blowering Reservoir 1 631 1 250 76% 24 1 226 +70

Eildon Reservoir 3 334 1 891 57% 100 1 791 +52

* 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 01 Sep 2020

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

Lake Eucumbene - Total 962 +6 Snowy-Murray +2 419

Snowy-Murray Component 418 +15 Tooma-Tumut +5 102

Target Storage 1 240 Net Diversion -3 317

Murray 1 Release +6 530

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) 25.3 98 Yarrawonga Main Channel (net) 1.5 8

Wakool Sys Allowance 0.6 19 Torrumbarry System + Nyah (net) 0 0

Western Murray Irrigation 0.1 1 Sunraysia Pumped Districts 1 4

Licensed Pumps 2.1 27 Licensed pumps - GMW (Nyah+u/s) 0 1

Lower Darling 0.0 0 Licensed pumps - LMW 3.6 14

TOTAL 28.1 145 TOTAL 6.1 27

* 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 and environmental flows.

Entitlement this month 135.0 *

Flow this week 65.0 (9 300 ML/day)

Flow so far this month 17.7 Flow last month 261.6

Salinity (EC) (microSiemens/cm at 25o C)

Current Average over the last week Average since 1 August 2020

Swan Hill 120 120 120

Euston - - -

Red Cliffs 150 160 140

Merbein 150 150 140

Burtundy (Darling) 290 280 310

Lock 9 140 130 130

Lake Victoria 120 120 120

Berri 150 150 140

Waikerie 240 220 200

Morgan 220 210 210

Mannum 190 210 220

Murray Bridge 250 250 240

Milang (Lake Alex.) 870 890 930

Poltalloch (Lake Alex.) 400 500 460

Meningie (Lake Alb.) 1 720 1 720 1 700

Goolwa Barrages 1 240 1 320 1 720

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River Levels and Flows Week ending Wednesday 02 Sep 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 - - - 2 340 F 1 610 4 860

Jingellic 4.0 2.07 208.59 7 780 R 8 310 14 610

Tallandoon ( Mitta Mitta River ) 4.2 1.63 218.52 1 090 F 1 160 1 360

Heywoods 5.5 1.40 155.03 600 S 600 600

Doctors Point 5.5 1.70 150.17 2 270 R 2 400 3 250

Albury 4.3 0.85 148.29 - - - -

Corowa 4.6 0.75 126.77 2 270 F 2 970 3 390

Yarrawonga Weir (d/s) 6.4 0.90 115.94 5 090 S 6 470 7 960

Tocumwal 6.4 1.46 105.30 4 950 F 7 140 6 870

Torrumbarry Weir (d/s) 7.3 4.44 82.98 15 390 F 13 830 7 860

Swan Hill 4.5 2.42 65.34 14 040 R 10 550 7 790

Wakool Junction 8.8 3.79 52.91 11 840 R 10 240 8 520

Euston Weir (d/s) 9.1 2.03 43.87 11 690 R 10 610 8 900

Mildura Weir (d/s) - - 10 150 F 9 640 7 450

Wentworth Weir (d/s) 7.3 3.06 27.82 9 270 F 8 740 6 990

Rufus Junction - 3.78 20.71 8 500 R 8 870 7 550

Blanchetown (Lock 1 d/s) - 0.77 - 8 000 S 8 090 7 770

Tributaries

Kiewa at Bandiana 2.8 1.87 155.10 1 770 R 1 940 2 600

Ovens at Wangaratta 11.9 9.50 147.18 5 030 F 6 000 6 710

Goulburn at McCoys Bridge 9.0 4.54 95.96 7 520 F 10 310 5 190

Edward at Stevens Weir (d/s) 5.5 1.45 81.22 1 210 F 930 430

Edward at Liewah - 1.29 56.67 700 F 840 920

Wakool at Stoney Crossing - 1.42 54.91 480 F 500 530

Murrumbidgee at Balranald 5.0 2.34 58.30 2 030 F 1 830 1 240

Barwon at Mungindi 6.1 3.43 - 650 F 670 180

Darling at Bourke 9.0 4.26 - 1 210 F 1 350 1 300

Darling at Burtundy Rocks - 0.71 - 160 F 160 170

Natural Inflow to Hume 13 840 22 850

(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 -0.13 - No. 7 Rufus River 22.10 +0.03 +1.46

No. 26 Torrumbarry 86.05 -0.00 - No. 6 Murtho 19.25 +0.10 +0.31

No. 15 Euston 47.60 +0.00 - No. 5 Renmark 16.30 +0.16 +0.46

No. 11 Mildura 34.40 -0.01 +0.28 No. 4 Bookpurnong 13.20 +0.26 +0.94

No. 10 Wentworth 30.80 +0.00 +0.42 No. 3 Overland Corner 9.80 +0.04 +0.50

No. 9 Kulnine 27.40 -0.00 +0.15 No. 2 Waikerie 6.10 +0.19 +0.43

No. 8 Wangumma 24.60 +0.04 +0.25 No. 1 Blanchetown 3.20 +0.15 +0.02

Lower Lakes FSL = 0.75 m AHD

Lake Alexandrina average level for the past 5 days (m AHD) 0.82

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 5 - Open Open -

Mundoo 26 openings 0.83 1 - - - Open

Hunters Creek - - - - Open - -

Boundary Creek 6 openings - 1 - Open - -

Ewe Island 111 gates - All closed - - - Open

Tauwitchere 322 gates 0.90 12 Open Closed Open -

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

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Week ending Wednesday 02 Sep 2020

State Allocations (as at 02 Sep 2020)

NSW - Murray Valley Victorian - Murray Valley

High security 97%

General security 12%

High reliability 32%

Low reliability 0%

NSW – Murrumbidgee Valley

Victorian - Goulburn Valley

High security 95%

General security 44%

High reliability 47%

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 : http://www.environment.sa.gov.au/managing-natural-resources/river-murray