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River Murray Weekly Report For the week ending Wednesday, 13 May 2020

Trim Ref: D20/15823

Rainfall and inflows Following on from recent wet weather, light to moderate rainfall continued across the southern Murray-Darling Basin this week (Map 1). For the upper Murray catchments, highest totals included 24 mm at Khancoban AWS on the upper River Murray in NSW and 29 mm at Rocky Valley on the Ovens River in Victoria. In South Australia, at either side of the Lower Lakes, 33 mm was recorded at Meningie and 28 mm at Goolwa.

In the northern Basin, falls were recorded in the upper reaches of the Border Rivers, including 22 mm at Pindari Dam.

Map 1 – Rainfall across the Murray-Darling Basin for the week ending 13 May 2020. Source: Bureau of Meteorology.

Stream flows have continued to recede this week following the significant rainfall event that occurred across late April and early May, after inflows reached levels not observed for several years. In the River Murray upstream of Hume, Biggara has now receded to 1,100 ML/day and Jingellic is currently 9,300 ML/day and falling after a small rise in response to rainfall mid-week.

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In the Kiewa River, the inflow to the River Murray, measured at Bandiana, continued to recede from 5,200 ML/day to the currently rate around 3,450 ML/day (Photo 1).

Photo 1 – Kiewa river at Bandiana is receding after higher flows from the recent rainfall (photo credit: Amber Craig, MDBA)

In the Ovens River, the flow just upstream of the River Murray at Peechelba continued to fall from 16,000 ML/day to the current rate near 6,800 ML/day.

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 at Bureau of Meteorology’s (BoM) website and in the Murray River Basin daily river report at the WaterNSW website.

In the 8-day rainfall outlook, the Bureau of Meteorology is currently forecasting rain with totals of up to around 25 mm possible in the upper Murray catchments. The Bureau of Meteorology’s latest three-month outlook (to August 2020) indicates a greater chance of wetter conditions across the Murray for winter. A return to wetter conditions will provide a much needed boost to the system and state allocations.

Although this recent rainfall and outlook is promising for the year ahead, the Executive Director of River Management has reminded the community that we are not yet out of the drought. Recent inflows, although very welcome, have so far only raised storage levels by a modest amount.

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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.

Across the system, all WaterNSW Dams and Recreation areas are closed to public access until further notice. In Victoria, boating restrictions have recently eased, including for recreational houseboat use, however caravan parks and camping areas remain closed. 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 Bushfire impacts - The MDBA and State Constructing Authorities are continuing to monitor water quality in areas affected by the summer bushfires in the upper Murray catchment, particularly following rainfall events. Mobilised ash and sediment have been observed in Lake Hume.

Risks to water quality remain from ash and sediment washing into the lake from bushfire affected areas. Re-growth of vegetation in less severely burnt areas is helping to reduce this risk through soil stabilisation. This process will take time and it is still possible that further fish deaths may result from poor water quality, particularly following intense rainfall.

Following the recent rainfall some locations such as Jingellic had short-lived increases in turbidity as ash was mobilised into the river. During this period oxygen levels remained within in healthy levels.

For information on current water quality and any impacts to your water supply, contact your retail water supplier.

There are currently no red alerts for blue-green algae in the River Murray system. However, there are a number of amber alerts that remain current along the river. 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 113 GL to 2,624 GL (32% capacity). Runoff from the recent rain will continue to flow into the upper Murray storages over the coming week with corresponding further storage improvements. Tributary inflows downstream of Hume Dam will make their way towards Lake Victoria over the next few weeks. This will see Lake Victoria storage rise over the coming month.

At Dartmouth Reservoir, the storage increased by 25 GL to 1,916 GL (50% capacity). The release from Dartmouth is targeting the minimum flow requirements, measured at Colemans of 200 ML/day.

At Hume Reservoir (Photo 2), the storage increased by 78 GL to 610 GL (20% capacity). Due to high tributary inflows downstream of Hume, the release from Hume is currently continuing at the minimum release of 600 ML/day.

• Upper Murray tributaries continue to recede • Releases downstream of Yarrawonga Weir reduced this week as Ovens and Kiewa recede • The peak flow along the River Murray currently at 14,500 ML/day at Swan Hill

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Photo 2 – Sunset at Lake Hume, which has increased to 20% with inflows from recent rainfall (Photo credit: Amber Craig, MDBA)

At Lake Mulwala, the pool level is currently 124.82 m AHD, which is within the normal operating range between 124.6 and 124.9 m AHD. With recent rain falling across the irrigation districts, the diversion to Yarrawonga Main Channel and Mulwala Canal have all but ceased and are unlikely to increase again as the irrigation season draws to a close for winter.

At Yarrawonga Weir, the release peaked around 24,000 ML/day on 6 May in response to inflows from the Ovens and Kiewa catchments. The release has reduced to around 10,000 ML/day as tributary inflows have receded and is expected to fall to around 9,000 ML/day in the coming days.

Further downstream, these high flows have required the Barmah-Millewa Forest regulators to be opened to manage the flow through the Choke as per normal operational practice. This will see a short period of inundation of the forest as water moves through this lower floodplain landscape. No environmental water has been used with this event. As the Yarrawonga Weir release is reduced the forest regulators will be progressively closed as the downstream flow drops to below channel capacity.

Flows through the Edward River offtake peaked near 1,900 ML/day this week. Flow through the Gulpa Creek offtake increased, reaching around 450 ML/day. Flow through the offtakes will reduce as flows in the River Murray recede over the coming week. Downstream on the Edward River at Toonalook, the flow is increasing as water from the Murray returns through the Millewa Forest. At Stevens Weir, the diversions through the Wakool River, Yallakool Creek and Colligen Creek offtake regulators have increased to 60 ML/day, 430 ML/day and 460 ML/day respectively. At Stevens Weir, the downstream flow increased from 1,100 ML/day to 1,900 ML/day and is expected to increase further over the coming week as the higher flows reach the weir.

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Back on the River Murray, the flow at Barmah is rising and is expected to increase further as flow through the creeks and anabranches of the Barmah Forest returns to the River Murray. The flow at Barmah is currently 7,300 ML/day and may reach around 9,000 ML/day in the coming week.

Inflow from the Broken Creek, measured at Rice’s Weir, decreased this week to near 220 ML/day. Without further rain, a rate of around 180 ML/day will be targeted, using environmental water to maintain winter base flows.

In the Goulburn River, the flow, measured at McCoys Bridge, has continued reducing following rainfall. The flow reached a peak of approximately 12,500 ML/day and has since reduced to the current rate around 2,500 ML/day. The flow will continue to decrease gradually over the coming weeks to target a minimum flow of around 540 ML/day. This target flow will be maintained on behalf of the Victorian Environmental Water Holder using environmental water if tributary inflows are not sufficient.

Delivery of Goulburn Valley IVT is not currently required to meet Murray system demands. 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 reduced this week to around 1,000 ML/day and are anticipated to reduce further in the coming week as the irrigation season closes. The Torrumbarry Weir pool remains at the Full Supply Level (FSL) of 86.05 m AHD. Planning is underway to vary the pool level at Torrumbarry Weir as part of the weir pool variability program. The pool is expected to be varied between FSL and up to 30 cm below FSL between June and August. The release from Torrumbarry Weir peaked just below 16,000 ML/day early this week in response to higher inflows from the Goulburn River. The release has fallen to around 11,700 ML/day and is expected to ease further over the coming weeks.

The peak flow in the River Murray, as a result of the rain in late April and early May is currently passing Swan Hill, where the flow reached around 14,500 ML/day.

Inflow from the Murrumbidgee River, measured at Balranald, averaged 350 ML/day this week. The Murrumbidgee IVT balance is open, with 0.9 GL able to be transferred in and 99.1 GL able to be transferred out.

At Euston, the weir pool level is targeting around 30 cm below FSL and will vary within the range of 20-30 cm below FSL over the coming months as part of the weir pool variability program. Varying pool levels helps restore a more natural wetting and drying cycle to riverbanks and adjacent wetlands within the influence of the weir pool. The downstream release increased this week from 6,000 ML/day to the current rate of 10,600 ML/day. The peak River Murray flow will reach Euston in the coming week, where flow may reach around 15,000 ML/day.

This week the Menindee Lakes storage increased by 51 GL to 404 GL (23% capacity). WaterNSW has been providing regular updates on the streamflow response in the Barwon-Darling system over the last few months and currently forecasts a volume in the order of 520 and 540 GL will flow into the Menindee Lakes. Further flow rises have occurred upstream of Bourke in the last few weeks following rainfall, and this is adding further uncertainty to the volume of water that will ultimately reach Menindee Lakes from current flows in the northern Basin. WaterNSW is closely monitoring inflows and storage volumes and announced a general security allocation for the Murray and lower Darling in its 15 May 2020 water allocation statement (see table on last page).

In managing the system, WaterNSW is moving water from Lake Wetherell to Lake Pamamaroo (now storing 180 GL) to maximise the storage efficiency in the lakes. Flow through the Pamamaroo inlet regulator is currently 10,000 ML/day. WaterNSW has also reduced the release at Weir 32 to a target of 200 ML/day. More information including, inflows and releases from the Menindee Lakes is available on the WaterNSW website.

Despite recent rainfall and streamflow responses, 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 will target around FSL (30.80 m AHD) but is expected to vary 10 cm above and below this level. River users are advised to adjust their activities, pumps and moorings to accommodate any

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changes in weir pool level. The downstream release is currently near 6,400 ML/day. The release is expected to gradually increase over the coming week as higher flows arrive from upstream.

At Lake Victoria, the storage volume increased by 10 GL to 292 GL (43% capacity). The storage will continue to rise across the month as higher river flows arrive from upstream and are captured in the lake.

The flow to South Australia reduced this week from 4,400 ML/day to the current rate of around 2,700 ML/day. Flow is expected to remain around this rate for the coming week, before increasing in the second half of the month. Delivery of South Australian entitlement is being varied within the month of May to maximise the capture of water in Lake Victoria. In the second half of May, higher flows from upstream will arrive and are likely to reach a rate that exceeds the flow requirements for South Australia and the channel capacity of the inlet to Lake Victoria. Lowering the delivery rate of South Australian entitlement now allows more of the higher flows, that cannot be captured in Lake Victoria due to the limited inlet capacity, to be used to meet South Australia’s entitlement, thereby maximising the water resource. In undertaking this operation, the total volume of South Australian Entitlement delivered in May remains the same. For more information on South Australia’s Entitlement flow, see the South Australian Department for Environment and Water’s latest River Murray flow report.

The Lower Lakes 5-day average water level is currently 0.57 m AHD. Releases have been occurring through fishways and opportunistic releases through Tauwitchere barrage. For information on barrage releases 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 13 May 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 3 856 450.02 1 916 50% 71 1 845 +25 Hume Reservoir 192.00 3 005 174.81 610 20% 23 587 +78 Lake Victoria 27.00 677 23.48 292 43% 100 192 +10 Menindee Lakes 1 731* 404 23% (- -) # 0 +51 Total 9 269 3 222 35% - - 2 624 +164 Total Active MDBA Storage 32% ^ Major State Storages

Burrinjuck Reservoir 1 026 421 41% 3 418 +7 Blowering Reservoir 1 631 813 50% 24 789 +3 Eildon Reservoir 3 334 1 406 42% 100 1 306 +45

* 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 12 May 2020 Storage Active Storage (GL) Weekly Change (GL) Diversion (GL) This Week From 1 May 2020 Lake Eucumbene - Total 910 n/a Snowy-Murray +13 21 Snowy-Murray Component 539 n/a Tooma-Tumut +6 17 Target Storage 1 290 Net Diversion 8 4 Murray 1 Release +22 42

Major Diversions from Murray and Lower Darling (GL) * New South Wales This Week From 1 July 2019 Victoria This Week From 1 July 2019 Murray Irrig. Ltd (Net) 0.1 139 Yarrawonga Main Channel (net) 0.9 127 Wakool Sys Allowance 0.7 54 Torrumbarry System + Nyah (net) 3.6 291 Western Murray Irrigation 0.1 23 Sunraysia Pumped Districts 0.4 106 Licensed Pumps n/a 131 Licensed pumps - GMW (Nyah+u/s) 1.5 26 Lower Darling 0.0 1 Licensed pumps - LMW 1.4 383 TOTAL 0.9 348 TOTAL 7.8 933

* 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 93.0 * Flow this week 19.9 (2 800 ML/day) Flow so far this month 46.1 Flow last month 120.8

Salinity (EC) (microSiemens/cm at 25o C) Current Average over the last week Average since 1 August 2019 Swan Hill 100 80 70 Euston - - - Red Cliffs - - 50 Merbein 120 110 90 Burtundy (Darling) 250 240 790 Lock 9 110 110 100 Lake Victoria 130 130 120 Berri 210 210 150 Waikerie 290 260 210 Morgan 240 230 220 Mannum 250 250 260 Murray Bridge 320 320 280 Milang (Lake Alex.) 950 950 890 Poltalloch (Lake Alex.) 760 740 820 Meningie (Lake Alb.) 1 580 1 610 1 790 Goolwa Barrages 10 060 8 400 2 620

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River Levels and Flows Week ending Wednesday 13 May 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 - - - 6 100 F 5 460 5 110 Jingellic 4.0 2.24 208.76 9 300 F 9 690 15 160 Tallandoon ( Mitta Mitta River ) 4.2 1.66 218.55 1 150 F 1 350 3 010 Heywoods 5.5 1.53 155.16 600 S 600 600 Doctors Point 5.5 2.00 150.47 4 210 F 4 260 6 110 Albury 4.3 1.09 148.53 - - - - Corowa 4.6 1.20 127.22 3 980 R 4 520 5 490 Yarrawonga Weir (d/s) 6.4 1.67 116.71 10 370 R 15 080 13 790 Tocumwal 6.4 2.36 106.20 11 180 F 16 980 9 590 Torrumbarry Weir (d/s) 7.3 3.58 82.13 11 650 F 14 350 5 680 Swan Hill 4.5 2.49 65.41 14 460 S 10 970 4 300 Wakool Junction 8.8 4.07 53.19 13 270 R 8 680 5 250 Euston Weir (d/s) 9.1 1.86 43.70 10 600 R 7 050 5 450 Mildura Weir (d/s) - - 5 830 F 5 360 5 180 Wentworth Weir (d/s) 7.3 2.87 27.63 6 260 R 5 280 5 280 Rufus Junction - - - - F 2 520 3 980 Blanchetown (Lock 1 d/s) - - - 1 120 F 2 610 3 860 Tributaries Kiewa at Bandiana 2.8 2.73 155.96 3 450 F 3 730 5 410 Ovens at Wangaratta 11.9 9.76 147.44 5 920 F 7 140 16 020 Goulburn at McCoys Bridge 9.0 2.32 93.74 2 530 F 5 850 5 930 Edward at Stevens Weir (d/s) 5.5 1.94 81.71 1 900 S 1 330 810 Edward at Liewah - 1.57 56.95 920 R 880 830 Wakool at Stoney Crossing - 1.42 54.91 470 R 450 430 Murrumbidgee at Balranald 5.0 0.66 56.62 340 F 350 290 Barwon at Mungindi 6.1 3.21 - 130 F 150 300 Darling at Bourke 9.0 4.32 - 1 710 F 3 220 9 710 Darling at Burtundy Rocks - 0.74 - 170 F 220 350 Natural Inflow to Hume 13 200 29 850

(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 -0.08 - No. 7 Rufus River 22.10 -31.10 -28.25 No. 26 Torrumbarry 86.05 +0.00 - No. 6 Murtho 19.25 -28.25 -25.30 No. 15 Euston 47.60 -0.25 - No. 5 Renmark 16.30 -25.30 -22.20 No. 11 Mildura 34.40 +0.03 +0.14 No. 4 Bookpurnong 13.20 -22.20 -18.80 No. 10 Wentworth 30.80 -39.80 +0.23 No. 3 Overland Corner 9.80 -18.80 -15.10 No. 9 Kulnine 27.40 -36.40 -33.60 No. 2 Waikerie 6.10 -15.10 -12.20 No. 8 Wangumma 24.60 -33.60 -31.10 No. 1 Blanchetown 3.20 -12.20 -9.75

Lower Lakes FSL = 0.75 m AHD Lake Alexandrina average level for the past 5 days (m AHD) 0.57

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

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

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Week ending Wednesday 13 May 2020

State Allocations (as at 15 May 2020)

NSW - Murray Valley Victorian - Murray Valley High security 97% General security 3%

High reliability 66% Low reliability 0%

NSW – Murrumbidgee Valley

Victorian - Goulburn Valley High security 95% General security 11%

High reliability 80% 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