River Murray System
Annual Operating Plan
End October 2011 Review
2011-12 Water Year
1 June 2011 – 31 May 2012
MDBA 12 January 2012
MDBA: D11/38061
River Murray System - Annual Operating Plan 2011-12 — End October 2011 Review
Table of contents
1 Introduction 1
2 System status on 31 October 2011 1
3 Summary of water sharing and significant operations 5
3.1 River Murray System initial scenarios for 2011-12 5
4 Detailed River Murray System operations for 2011-12 19
4.1 River and storage losses 19
4.2 Changes to minimum flow rates 20
4.3 Weir pool level manipulation 20
4.4 Delivering environmental water 21
4.5 Dartmouth Reservoir 23
4.6 Hume Reservoir and flows at Doctors Point 25
4.7 Lake Mulwala and the Barmah Choke 28
4.8 Euston Weir release outlook 29
4.9 Lake Victoria 31
4.10 Menindee Lakes 33
4.11 Flow to South Australia 36
4.12 Lower Lakes and Barrage operation in South Australia 38
4.13 Maintenance/construction at Locks and Weirs and TLM sites 40
5 Calendar of future events in 2011-12 42
6 Further information on River Murray System operations 43
List of Figures
Figure 1 Rainfall Deciles – 6 months 1 May 2011 to 31 October 2011 6
Figure 2 River Murray System inflows (excluding inflows to Menindee and Snowy Mountains Scheme) – June 2011 to current and long-term averages 7
Figure 3 Inflows to Menindee Lakes 2007-08 to Oct 2011 7
Figure 4 MDBA active storage June 2000 to Oct 2011 8
Figure 5 Ranked Historical System Inflows showing years similar to initial scenarios 10
Figure 6 River Murray System conveyance losses upstream of the SA border 22
Figure 7 Impact of environmental flow releases on flow rates at Yarrawonga Weir 24
Figure 8 Original Dartmouth Reservoir storage outlook 26
Figure 9 End October Dartmouth Reservoir storage outlook 26
Figure 10 Original Dartmouth Reservoir release outlook 27
Figure 11 End October Dartmouth Reservoir release outlook 27
Figure 12 Original Hume Reservoir storage outlook 29
Figure 13 End October Hume Reservoir storage outlook 29
Figure 14 Hume Reservoir release outlook – flows at Doctors Point 30
Figure 15 Hume Reservoir release outlook – flows at Doctors Point 30
Figure 16 Yarrawonga Weir release outlook 31
Figure 17 Yarrawonga Weir release outlook 32
Figure 18 Original Euston release outlook 33
Figure 19 End October Euston release outlook 33
Figure 20 Original Lake Victoria storage outlook 35
Figure 21 End October Lake Victoria storage outlook 35
Figure 22 Original Menindee Lakes storage outlook 37
Figure 23 End October Menindee Lakes storage outlook 37
Figure 24 Original Menindee Lakes release outlook 38
Figure 25 End October Menindee Lakes release outlook 38
Figure 26 Original Forecast flows to SA 40
Figure 27 End October Forecast flows to SA 40
Figure 28 Lake Alexandrina level and EC for Lakes Albert and Alexandrina 41
List of Tables
Table 1 Storage in MDBA major reservoirs on 31 October 2011 8
Table 2 Details of each initial scenario in 2011-12 Operating Plan (GL) 10
Table 3 Summary of Water Availability under each scenario 12
Table 4 Summary of significant river operations under each scenario 15
Table 5 Summary of significant environmental operations under scenarios 17
Table 6 The Living Murray works to improve environmental outcomes 42
Table 7 Works to improve current structures 43
MDBA 12 January 2012 7
River Murray System - Annual Operating Plan 2011-12 — End October 2011 Review
1 Introduction
The River Murray System Annual Operating Plan for the 2011-12 (Operating Plan) water year (1 June 2011 to 31 May 2012) was released in August 2011 and provided context and descriptions of how the River Murray System (the System) may have been operated under a number of assumed scenarios.
This document provides an update of the Operating Plan and compares actual river operations up to 31 October 2011 with the six scenarios that were presented in the Operations Plan. The review also describes the current system conditions and potential river operations over the remainder of the year. Variations to the initial Operating Plan are provided as are descriptions of river operations that may be undertaken during the remainder of 2011-12 that were not documented in the initial Operating Plan.
There are three significant operations that have, or may be carried out, that were not documented in the Operating Plan: a temporary drawdown of Mildura Weir to assist in essential maintenance works (section 4.3), an increase in the volume of environmental water to be delivered to South Australia during summer/autumn (section 4.4) and variable patterns for minimum releases from Menindee Lakes and Dartmouth (section 4.2).
UPDATE 12 December 2011 In late November and early December 2011 (during publication of this report) there were significant rain events in some catchments of the upper Darling, including the Namoi, Gwydir, and Border Rivers. The impact of this rainfall on inflows to Menindee Lakes will not be known for several months. However initial indications are that there will be >1,200GL of inflow to Menindee Lakes between late December 2011 and end February 2012. In this Revised Operating Plan, the assumed inflow volume between January and May 2012 in the Wet Scenario is 1,500 GL while in the Very Wet it is about 3,000 GL. Therefore, it is most likely that the Menindee Lakes, the lower Darling River and Murray downstream of Wentworth will track more closely to the Wet and Very Wet scenarios than to the drier scenarios for the remainder of 2011-12. For the Murray upstream of Wentworth, there was above average rainfall during November however it is still possible that some outcomes identified in the drier scenarios may eventuate.
2 System status on 31 October 2011
Rainfall across the southern Basin and in the upper Murray catchment, where the majority of the system inflows are usually generated, between 1 May 2011 and 31 October 2011 was either average or below average (Figure 1).
In the south of the Basin, River Murray System inflows (excluding Snowy releases and Menindee inflows) totalled 5,500 GL between 1 June 2011 and 31 October 2011, which has an Annual Exceedance Probability (AEP) of around 55%.
As can be seen in Figure 2, although rainfall has been below average, the catchment conditions remained wet after the high rainfall experienced earlier in the year and inflows remained above the long term average during winter. However, as below average rainfall continued into spring, the catchments began to dry up and hence inflows in September and October were below long term averages, with an AEP of about 70%.
In the north of the Basin, flows in the Barwon-Darling system have continued to dissipate since the peak flood flows in early 2011. There have been small inflow events from the Border Rivers and Namoi catchments; however the flow in the Darling at Wilcannia has averaged only about 1,000 ML/day during September and October 2011.
Total inflows to Menindee Lakes between 1 June 2011 and 31 October 2011 were about 186GL (Figure 3), which has an AEP of around 50%. Release from Menindee has been averaging 15 GL/month and this release along with evaporation has meant the water level in the lakes has been gradually falling since August 2011. The BoM has forecast there to be a good chance of above average rainfall in the Darling catchment over the period from November 2011 to January 2012.
System storage has improved since 1 June 2011 when the total MDBA storage was at 7,564GL. The total MDBA storage on 31 October 2011 was 8,193GL (Table 1 and Figure 4), including about 1,859GL in Menindee Lakes. The active storage of 7,580 GL in October was the highest active storage since December 2000. On 31 October 2011, there was also around 380GL of water available to the Murray in 2011-12 held in storages in the Murrumbidgee and Goulburn Valleys as a result of earlier trade into the Murray.
Figure 1 Rainfall Deciles – 6 months 1 May 2011 to 31 October 2011
Figure 2 River Murray System inflows (excluding inflows to Menindee and Snowy Mountains Scheme) – June 2011 to current and long-term averages
Figure 3 Inflows to Menindee Lakes 2007-08 to Oct 2011
Table 1 Storage in MDBA major reservoirs on 31 October 2011
Major storage / Total capacity (GL) / Active capacity (GL) / Total water in storage on 31/5/11 (GL) / Percentage of total capacity / Active water in storage on 31/5/11 (GL) / Total water in storage on 31/10/11 (GL) / Percentage of total capacityDartmouth Reservoir / 3,856 / 3,785 / 2,444 / 63% / 2,373 / 2,850 / 74%
Hume Reservoir / 3,005 / 2,982 / 2,812 / 94% / 2,789 / 2,838 / 95%
Lake Victoria / 677 / 577 / 375 / 55% / 275 / 646 / 96%
Menindee Lakes / 1,731 / 1,251 / 1,933 / 112% / 1,453 / 1,859 / 107%
River Murray System Total / 9,352 / 8,595 / 7,564 / 81% / 6,890 / 8,193 / 88%
Figure 4 MDBA active storage June 2000 to Oct 2011
3 Summary of water sharing and significant operations
3.1 River Murray System initial scenarios for 2011-12
Since the inflows to the River Murray System cannot be known in advance, the initial Operational Plan addressed the operations that may have been undertaken under six different scenarios that covered a range of conditions that may have been experienced.
Each scenario had in-built assumptions regarding inflows from the Snowy scheme, unregulated inflows into Hume Reservoir, inflows into Dartmouth Reservoir and inflows from the tributaries, including the Kiewa, Ovens, Goulburn, Murrumbidgee, and Darling Rivers, conveyance “losses”, storage losses and usage patterns.
Generally, it is only the volume of water available under the ‘worst case scenario’ (and updates thereof) that is progressively allocated by the States to their water users. The other scenarios are used to provide indicative quantities of water availability to the States to assist yearly planning for water managers and customers should those wetter scenarios eventuate.
The relative difference between yearly inflows of each of the six scenarios can be compared in Figure 5. The details of the six scenarios are provided in Table 2 and they are labelled according to the assumed River Murray System inflow as follows:
· the ‘worst case scenario’, assumes about 1,300 GL of River Murray System inflows for all of 2011-12, which is 650GL more than the normal ‘worst case scenario’ adopted in recent years of 650 GL. The assumed inflows are greater due to forecast high inflows for the remainder of June 2011 and water in transit along the Murrumbidgee River that is expected to reach the Murray during July 2011;
· the ‘dry’ scenario, assumes River Murray System Inflows of about 2,900 GL for all of 2011-12, which is comparable to inflows in 2009-10;
· the ‘moderate’ scenario, assumes River Murray System Inflows of about 4,200 GL for all of 2011-12 which is comparable to inflows in 2001-02;
· the ‘near average’ scenario, assumes River Murray System Inflows of about 6,300GL for all of 2011-12 which is comparable to inflows in 2005-06; and
· the ‘wet’ scenario, assumes River Murray System Inflows of about 11,200 GL for all of 2011-12 which is slightly higher than in 2000-01; and
· the ‘very wet’ scenario, assumes River Murray System Inflows of about 18,100 GL for all of 2011-12 which is slightly higher than in 2010-11.
Figure 5 Ranked Historical System Inflows showing years similar to initial scenarios
Table 2 Details of each initial scenario in 2011-12 Operating Plan (GL)
State water entitlements and significant decisions on river operations are primarily driven by the timing and location of inflow events and usage patterns. For the six scenarios outlined in Section 3.1 of this plan, Table 3. provides a summary of the initial outlooks for water availability; Table 4 provides a summary of the initial outlooks for important operational decisions that may need to be made while Table 5 provides the initial outlooks to assist environmental management. The final column in each table provides an indication of the current status or any additional information as a 31 October 2011.
MDBA 12 January 2012 7
River Murray System - Annual Operating Plan 2011-12 — End October 2011 Review
Table 3 Summary of Water Availability under each scenario
WATER AVAILABILITY / ‘worst case’ / Dry / Moderate / Near average / Wet / Very Wet / Current status as at 31 Oct 2011 /Sharing rules at end of May 2012 / Tier 1 / Tier 1 / Tier 1 / Tier 1 / Tier 1 / Tier 1 / Tier 1
Indicative water entitlements at end May 2012
NSW
VIC
SA / 1910 GL
2140 GL
1154 GL / 2530 GL
3020 GL
1154 GL / 2830 GL
3400 GL
1154 GL / 3370 GL
3780 GL
1154 GL / 4220 GL
4530 GL
1154 GL / 4100 GL
4980 GL
1154 GL / “worst case” forecast 2,500 GL 3,240 GL 1,154
SA Dilution & Loss / 696 GL / 696 GL / 696 GL / 696 GL / 696 GL / 696 GL / 696 GL
Carryover trade delivery to SA / 33 GL / 33 GL / 33 GL / 33 GL / 33 GL / 33 GL / 33 GL
Conveyance Reserve for 2012-13 / 225 GL / 225 GL / 225 GL / 225 GL / 225 GL / 225 GL / 225 GL
Forecast Minimum Reserve
at end May 2012 / 480 GL / 835 GL / 835 GL / 835 GL / 835 GL / 835 GL / 835 GL
Special Accounting / 3 States commence special accounting in August / No special accounting for entire year / No special accounting for entire year / No special accounting for entire year / No special accounting for entire year / No special accounting for entire year / NSW commenced special accounting in August 2011, but it is expected to cease prior to end 2011-12
Internal spill at Lake Victoria (Vic to NSW) / 0 GL # / 0 GL # / <10 GL # / 20 GL # / 50 GL # / 0 GL # / None as of 31 Oct 2011 but still possible over coming months
Lindsay River Allowance / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011 / Normal Lindsay River Allowance from 1 July 2011
Additional Dilution Flow / ≈ 440 GL # / ≈ 450 GL # / ≈ 630 GL # / ≈ 780 GL # / 1095 GL (all year) / 1095 GL (all year) / 660 GL forecast in “worst case” scenario
Unregulated Flows / ≈ 260 GL / ≈ 470 GL / ≈ 900 GL / ≈ 2220 GL / ≈ 6440 GL / ≈ 15,530 GL / 3,370 GL delivered prior to ceasing in early November. Potential for recommencement
Assumed usage
NSW
VIC
SA Ent. Delivered / #
1700 GL
1400 GL
1850 GL * / #
1900 GL
1500 GL
1850 GL * / #
1900 GL
1500 GL
1850 GL * / #
1900 GL
1500 GL
1850 GL * / #
1900 GL
1500 GL
1850 GL * / #
1300 GL
1200 GL
1850 GL * / 1,800 GL
1,500 GL
1,850 GL
End of season active storage / ≈1700 GL # / ≈3400 GL # / ≈4100 GL # / ≈5200 GL # / ≈6700 GL # / ≈8000 GL # / ≈3,645 GL in revised “worst case”; ≈4,800 GL in revised Near Average scenario
# Highly dependent on the timing of improvements in water availability and usage patterns