Environment and Natural Resources Committee

Inquiry into Flood Mitigation Infrastructure in

Submission by Goulburn-Murray Water

August 2011

#3221810

ii

Table of Contents

1 Introduction ...... 1 2 Response to ToR(a) – Flood Mitigation ...... 2 2.1 Operating Context ...... 3 2.1.1 Parliamentary Public Works Committee ...... 3 2.1.2 Water Act ...... 3 2.1.3 Bulk Entitlement Orders ...... 3 2.1.4 Emergency Management Manual Victoria ...... 4 2.2 Management Policies and Procedures ...... 4 2.2.1 Policy, Flood Operation of Goulburn-Murray Water‟s Headworks Structures .... 4 2.2.2 Procedures, Operations ...... 4 2.2.3 Procedures, Channel Operation ...... 6 2.3 G-MW Flood Operations 2010/11 ...... 7 2.3.1 BoM Seasonal Outlook ...... 7 2.3.2 Cairn Curran Flood Operations ...... 7 2.3.3 Eppalock Flood Operations ...... 11 2.3.4 Channel Flood Operations ...... 12 3 Response to ToR(b) – Levees ...... 14 3.1 G-MW Flood Protection Assets ...... 14 3.1.1 Loch Garry ...... 14 3.1.2 Beattie Depression ...... 14 3.1.3 Little Murray Weir ...... 15 4 Response to ToR(c,d & e) – vegetation management in waterways ...... 16 5 Comments and Learnings ...... 17 5.1 Communications, Consultation and Preparation ...... 17 5.1.1 Flooding of the Loddon House Caravan Park at Baringhup ...... 17 5.1.2 Municipal Flood Plans ...... 18 5.1.3 General Community Expectation ...... 18 5.2 Outcomes of G-MW Debriefs and Reviews ...... 19 Appendix A. – Parliamentary Public Works Committee Reports Appendix B. – Board Policy on Flooding Appendix C. – Presentation to Open Public Hearing Appendix D. – Hansard Transcript of Presentation to Open Public Hearing Appendix E. – Loddon and Campaspe Bulk Entitlement Orders

Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

1 Introduction

Goulburn-Murray Water (G-MW) provides this submission to the Inquiry into Flood Mitigation Infrastructure in Victoria conducted by the Environment and Natural Resources Committee to outline its role in the management of water supply infrastructure in Northern Victoria and to provide background information on its operations during the recent flood events.

G-MW is Victoria‟s largest Rural Water Corporation, managing 16 major and an extensive irrigation channel network across Northern Victoria. From September 2010 to January 2011, flooding was experienced across most of the region. During that time G-MW experienced flooding through all of its dams, with the exception of Eildon in the upper Goulburn catchment and Lake Dartmouth in the Mitta Mitta catchment. Large areas of the irrigation channel network were also affected by flooding.

The focus of this submission is the January 2011 event which resulted in record flooding in the Loddon and Campaspe catchments. The event involved the operation of Tullaroop, Cairn Curran and Laanecoorie dams in the Loddon catchment and Eppalock dam in the Campaspe catchment. Large areas of the Rochester, Loddon Valley and Torrumbarry irrigation areas were affected by floodwaters and suffered significant damage.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

2 Response to ToR(a) – Flood Mitigation

Identifying best practice and emerging technology for flood mitigation and monitoring infrastructure including river gauges

G-MW‟s dams and channels are not generally designed or intended to be operated as flood mitigation structures.

The dams are designed and operated to harvest, store and release bulk water for downstream entitlement holders. The majority of the water is owned by irrigators, urban water corporations or environmental water managers. Where possible the dams are operated to provide some limited flood mitigation benefit by delaying the onset of a flood and reducing the flood peak. The amount of flood mitigation provided depends on the size of the flood event and the water level in the dam prior to the event.

G-MW has dams with either fixed crest spillways or gated spillways. Fixed crest spillway dams generally have relatively small outlet works and operate on a „fill and spill‟ basis. As inflows enter the dam, the water level in the dam increases until it reaches the spillway crest level where it will overflow into the downstream river channel. The fixed crest level is at the Full Supply Level (FSL) of the dam and is the point at which the dam is 100% of capacity. The embankment of the dam is designed to allow the water level to naturally surcharge above 100% of capacity and allow the spillway structure to „throttle‟ outflow. Dams of this type provide some flood mitigation by attenuating the flood peak, section 2.3.3 shows this effect for the January flood through Eppalock. There is no operational control from the dam operator in passing floods through these types of dams.

Gated spillway dams are configured with large gates in the spillway that enable water to be stored above the spillway crest level. As the dam‟s FSL is above the spillway crest level, the gates must be closed to allow the dam to fill to 100% of capacity. During winter and spring, water is harvested in the dam by following a target filling curve that balances resource increases against a degree of flood mitigation. Flood water is passed through the spillway by opening the spillway gates. The embankments on G-MW‟s gated spillway dams are not designed to be surcharged in the same way fixed crest spillway dams operate. The flood operating procedures for gated spillways aims to pass inflows through the dam while maintaining the level within the dam at or below FSL. Generally the operation of gated spillway dams involves using any air space (the available volume between the lake level at the beginning of an event and FSL) to delay the onset of flooding and reduce the flood peak. The amount of flood mitigation that can be provided depends on the amount of air space available and the size of the flood. Only 3 of G-MW‟s 16 dams have gated spillways – Eildon, Buffalo and Cairn Curran. The passage of flood waters through Cairn Curran during November and January is presented in section 2.3.2.

The G-MW channel network is designed to provide water to irrigation customers through gravity flow. As a delivery system, the capacity of the channels decreases away from the point of origin. Channels at the beginning of the network are large (transmission capacities of approximately 3,000 ML/d), while those at the end of the network are much smaller (20 ML/d or less). As the channels supply water under gravity, the channels are, by necessity generally above natural surface. In flooding situations, the raised channel banks can redirect floodwaters. G-MW attempts to reduce the impact of the channels by closing control structures and allowing floodwaters to follow natural paths and pass over the channels.

In a number of locations, the channel system is piped under natural flood paths through syphons or has the natural path piped beneath through subways. These structures also

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water ensure that as much as possible flood water continues on its natural path. Refer to Section 2.2.3 for further detail.

G-MW operates an extensive river gauging network across each catchment for water quantity and quality monitoring purposes. Key sites at storages and in the upper catchments provide real time flow data for day-to-day operations including flood routing. Data from these sites is also available in real time to the Bureau of Meteorology (BoM). The gauging sites are serviced and maintained under the Regional Surface Water Monitoring Partnership which is administered by the Department of Sustainability and Environment (DSE).

2.1 Operating Context

2.1.1 Parliamentary Public Works Committee

The dam infrastructure managed by G-MW was constructed by the State Rivers and Water Supply Commission (SR&WSC). The intent and purpose of the infrastructure is described in the Parliamentary Public Works Committee (PPWC) reports.

The PPWC report and evidence describing Eppalock dam discusses the flood mitigation benefit the dam provides to Rochester, Elmore and Echuca. The information provided in section 2.3.3 of this submission on the operation of Eppalock during the January 2011 event demonstrates the dam functioned as intended by the PPWC.

The PPWC report on Cairn Curran does not mention flood mitigation at all.

2.1.2 Water Act

G-MW has functions and powers under the Water Act 1989 (the Act) to provide, manage and operate an irrigation district (section 221), a water district (section 163) and a waterway management district (section 189).

The function of G-MW as a storage manager appointed by the Minister for Water is prescribed by section 122ZL of the Act which in summary states it shall: Protect water system ecological values; Protect reliability and quality; Minimise environmental impacts; and Mitigate flooding where possible.

Detail of how G-MW addresses flood mitigation is provided in section 2.2.

2.1.3 Bulk Entitlement Orders

G-MW operates its dams and distribution systems under bulk entitlement orders established under the Act. The bulk entitlement orders establish the right to use and supply water under specific conditions and obligations. The bulk entitlement orders require G-MW to release water only for the purposes of supplying entitlement holders, and in limited cases, to protect water quality; there is no scope given to G-MW to release water from storage for flood mitigation purposes.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

The sole exception to this obligation occurs in the Goulburn bulk entitlement order, which contains a schedule that requires G-MW to follow specified target filling arrangements which seek to balance water resource availability and capacity for flood mitigation.

However, where G-MW can be reasonably assured that a pre-release can be made without adversely impacting on water resource availability (ie the storage will refill at the completion of a flood event) then pre-releases are made.

2.1.4 Emergency Management Manual Victoria

The Victorian Emergency Management Manual details the roles and responsibilities in emergency events. For flooding, the Victorian State Emergency Service (VICSES) is the lead agency and has responsibility to coordinate the emergency response. The Bureau of Meteorology (BoM) is responsible for issuing flood warnings. Municipal Councils are required to provide community awareness, information and warning systems and also identify and treat risks including flood.

The role of Water Authorities such as G-MW is to operate the assets appropriately. G-MW has developed and maintained flood operating procedures for all of its dams and channels which are discussed in section 2.2.

2.2 Management Policies and Procedures

2.2.1 Policy, Flood Operation of Goulburn-Murray Water’s Headworks Structures

G-MW operates its dams in accordance with a Board-approved policy on flood operation which states “the primary objective of flood operation is to ensure that Full Supply Level is not exceeded for longer than necessary, and that the peak outflow from the does not exceed peak inflow”. Also the specific policy statement is “The primary purpose of flood operation is to ensure the safety of Goulburn-Murray Water’s headworks structures. Surcharging of storages is not permitted, except in accordance with documented operational procedures for the structure approved by the manager Headworks.”

Specific flood operation procedures have been developed and are maintained and tested regularly. Details of these procedures are outlined below.

2.2.2 Procedures, Dam Operations

G-MW maintains comprehensive flood operations procedures for each of its gated spillway dams. Specific, but less detailed, flood operations procedures are included in the operations and maintenance manuals for the fixed crest spillway dams.

The flood operating procedures cover issues such as target filling arrangements, pre-release, flood mitigation and flood routing. They describe communications requirements with the community, emergency agencies, BoM and internal stakeholders. Roles and responsibilities are clearly described in each manual. Each year storage operations staff work through desk top exercises in emergency response and flood routing.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

A generic description of the operation of G-MW dams (including flood operations) can be summarised as: In a normal year during winter and spring, outflows from the dam are reduced and inflows are harvested for the coming irrigation season. Gated storages are filled in accordance with target filling arrangements which aim to manage the storage levels from May to October to have the dam full for the next irrigation season. This means that while the storage is in its filling cycle there is air space to assist in mitigating floods. If very high flood inflows are experienced during winter and spring the dam can be filled to reduce downstream flooding and then the water is released to return the storage level to the defined target filling arrangements. The filling of fixed crest dams is not managed to specific filling arrangements; instead, the level increases with inflows until FSL is reached. Note: Only the Goulburn Bulk Entitlement Order specifies the use of target filling arrangements. The gated storages in the Loddon and Buffalo catchments have used target filling arrangements developed from the historic record and past experiences for many years. As the filling cycle progresses through the year, the storage level will increase and thereby reduce the opportunity for flood mitigation. The operating aim is to store and retain as much water as possible in the dam during the irrigation season. In wet years like 2010 and the beginning of 2011, this means the storage will be maintained at or near 100% full during the summer months. In the event of high rainfall being forecast by the BoM, the procedures for flood management provide for water to be pre-released to create some air space. This is intended to provide some delay to the downstream flooding impacts and some reduction to the flood peak. It is not intended to eliminate all downstream flooding. How much to pre-release from the dam is a judgement made by G-MW based on the best advice available from the BoM. Short-term (eight day) rainfall forecasts are available, but the final four days of the forecast period comprise total accumulated rainfall only. Therefore, the rainfall forecast effectively only provides four days of reliable daily data. Even then, the forecasts do not describe the intensity or likely times of rainfall. It is recognised that the BoM‟s Forecast Explorer product is providing sub-daily rainfall forecasts, but G-MW is currently reliant on the expert advice obtained from the hydrologists of the BoM‟s Victorian Regional Office. There are limits to the flows that can be pre-released due to the risk of causing downstream flooding impacts before the rain event has even occurred. For example, the threshold for the minor flood level downstream of Laanecoorie is only 2,000 ML/d. Water released from Cairn Curran takes about 1 day to reach Laanecoorie. Any significant pre- releases from Cairn Curran could cause flooding impacts downstream of Laanecoorie, even though flooding immediately downstream of Cairn Curran is averted. Once a flood event is expected, G-MW may begin pre-releasing water within the downstream river channel capacity to create some air space if none is available. This may be 4-5 days prior to the rain event. If the rain event does occur –it is not always that forecast rain eventuates – and inflows to the dam begin to increase, the releases from the dam will be increased to match the inflow. If the event is forecast to continue to increase G-MW will inform the BoM, VICSES, Local Government and other stakeholders (specific to each site) of the likelihood of a flood event downstream of the dam. If the event continues to escalate, G-MW remains in regular contact with the BoM for forecasting information and to advise of likely river levels to enable flood warnings to be issued. As with any flood that is managed through a G-MW gated spillway dam, the flood procedures provide for the calculated inflow to be passed through. The aim is to not pass more than is coming into the dam and to also limit the time the level is above the maximum (100%) storage level.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

2.2.3 Procedures, Channel Operation

All of the G-MW Gravity operational areas have a “Flood Operation” plan. These plans indicate where G-MW assets need to be operated to minimise impacts on assets and landholders and as much as possible ensure flood water continues on its natural path. G-MW does not generally operate the irrigation or drainage infrastructure to manage flood water. There is minimal opportunity to utilise the irrigation network and drainage system to manage overland floods. The volumes of water in overland flooding events can be at least an order of magnitude greater than the capacity of the irrigation or drainage network.

As discussed in section 2, syphons pipe irrigation channels below defined waterways and subways pass waterways and floodways below channels. Syphons and subways are the primary method of allowing flood water to pass G-MW‟s irrigation infrastructure. The structures located within irrigation areas are designed to pass the flow resulting from a 1 in 10 year rainfall event. Where major carriers (such as the Waranga Western Channel), cross natural waterways or flood paths, the structure‟s capacity is designed on historic data to ensure that flood waters do not overtop the channel bank and place the channel asset at risk. In a small number of locations, flood water is allowed to enter an irrigation channel and then pass out of the channel via a fixed crest spillway or a structure that is operated to ensure the flood water continues on its natural path.

During major floods events, G-MW shuts down the irrigation channel network by closing regulating structures. This action allows overland flows that may enter channels to exit as close as possible to the entry point and follow natural flow paths, and has the aim of preventing, as much as possible, flood water being transferred along channels and affecting other landowners.

G-MW also has a drainage channel network, which is generally self regulating and is only designed to remove irrigation induced runoff from a designated summer rainfall event. G-MW has virtually no ability to actively manage flood flows in the drainage network during major floods.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

2.3 G-MW Flood Operations 2010/11

2.3.1 BoM Seasonal Outlook

According to the BoM three month forecast from November 2010 to January 2011 (Figure 1), there was about a 60% chance of the median rainfall being exceeded. The BoM forecast was not biased strongly enough toward wet conditions to justify maintaining a large volume of airspace in any of G-MW‟s dams to mitigate floods of the magnitude observed in either the November or January floods.

Cairn Curran Floods

Figure 1: Seasonal Outlook for South-East November 2010 to January 2011

The median rainfall for the Loddon catchment is 88 mm. The actual rainfall experienced during the November to January period was approximately 400 mm, with 100 mm of falling on one day in January.

2.3.2 Cairn Curran Flood Operations

The operating procedures for managing floods through the Cairn Curran Dam are governed by the „Cairn Curran Dam: Flood Management Rules (2007)‟. The manual outlines what considerations should be made for flooding occurring at the storage as well as actions to be taken in the event of a flood. The purpose of the flood management rules is in „achieving as much flood mitigation as possible, consistent with the primary focus of dam safety‟ as stated in the document. It also states „The provision of airspace after the 1 August will be governed by seasonal conditions including irrigation demand. The aim should be to ensure that the reservoir is full prior to an irrigation demand emerging.‟

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Seasonal outlooks, as can be accessed from the BoM website, did not provide sufficient evidence to warrant the maintaining of large volumes of flood mitigation airspace in Cairn Curran after 1 August. In addition, the months following August are when peak irrigation demand is expected and irrigation releases would usually be made from the storage. As outlined in the flood management rules, „The nature of catchment is such that inflows can recede quickly. Therefore, it is important that pre-releases for flood control do not compromise water harvesting‟.

Throughout the 2010-11 season G-MW operated the water levels in Cairn Curran in accordance with Target Filling Curve provisions of the Flood Management Rules.

For each of the flood events in the 2010/11 season, pre-releases were made from Cairn Curran based on information obtained from weather forecasts and discussions with Bureau of Meteorology forecasters.

The two graphs below are the hydrographs of inflows and outflows for Cairn Curran during the late November and January flood events. The red line represents the rate of inflow into the storage (in ML/d) while the blue line represents what is being released through the Cairn Curran spillway gates.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Cairn Curran November Flood

The highest inflows during this event were Saturday 27 and Sunday 28 November. Releases from Cairn Curran commenced on Wednesday 24 November as some rain which fell as thunderstorms had been received in the catchment over the previous few days. On Friday 26 November, releases increased to 3,500 ML/d following further rain in the catchment. The initial flood watch issued on the Friday afternoon indicated minor flooding was possible with the rain forecast. Minor flooding downstream of Cairn Curran does not pose an issue at the Loddon House Caravan Park at Baringhup.

In the 48 hours to 9 am Sunday, 88 mm of rainfall was recorded at Cairn Curran. The rainfall forecast for Saturday that was released on Saturday morning was initially for 40 mm. Rainfall forecasts were revised during Saturday as the rain fell and by late in the evening it was evident that 100 mm was likely. Higher rainfall was recorded on the ranges.

With reference to Figure 2 below, the key points of Cairn Curran operation can be summarised as:

Section A – inflows peaked at 52,000 ML/d and had began falling while releases were 48,000 ML/d demonstrating that releases from the storage did not exceed the outflows.

Section B – As releases were being reduced to bring the releases below the minor flood level, the storage began to rise again.

Cairn Curran Hydrograph: November Event

60,000 208.60 FSL 208.50 208.40 208.30 50,000 A 208.20 Airspace (level below full 208.10 supply level) prior to event 208.00 40,000 207.90 207.80 207.70 B 207.60 30,000 207.50 207.40 Major Flood 207.30

20,000 207.20 (m AHD) Level Storage Moderate Flood

207.10 Release/ Computed Release/ Inflow (ML/d) 207.00 206.90 10,000 Minor Flood 206.80 206.70 206.60 0 206.50

25/Nov 6:00 26/Nov 0:0026/Nov 6:00 27/Nov 0:0027/Nov 6:00 28/Nov 0:0028/Nov 6:00 29/Nov 0:0029/Nov 6:00 30/Nov 0:00 25/Nov 12:0025/Nov 18:00 26/Nov 12:0026/Nov 18:00 27/Nov 12:0027/Nov 18:00 28/Nov 12:0028/Nov 18:00 29/Nov 12:0029/Nov 18:00

Computed Inflow Release Storage Level FSL

Figure 2: Hydrograph for Cairn Curran Operations in November 2010

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Cairn Curran January Flood

Rainfall forecasts for Tuesday 11 to Wednesday 12 January were up to 100 mm, and about 85 mm was received at Cairn Curran with higher totals recorded on the ranges. From 50 to 100mm of rain was forecast for Thursday 13 and Friday 14 January; in excess of 100 mm was recorded at Cairn Curran over this period.

The hydrograph for Cairn Curran operations during January 2011 is presented in Figure 3. The key features of the operations are summarised as follows.

Section A – about 7,000 ML, or 0.5 metres, of airspace created prior to event. Airspace was utilised to keep water out of the Caravan Park during 12 and 13 January. If inflows were followed, the Caravan Park would have been inundated at 4pm on 12 January as opposed to 2pm on 13 January.

Section B – during the afternoon of 13 January and into 14 January, releases were increased inline with inflows to limit the volume of water held above full supply level. The dam was briefly surcharged above full supply to reduce the downstream flood peak.

Section C – inflows peaked at 90,000 ML/d and began falling while releases were 80,000 ML/d demonstrating that releases from the storage did not exceed the inflows.

Cairn Curran Hydrograph: January Event 100,000 208.70 208.60 90,000 208.50 FSL 208.40 208.30 80,000 208.20 C 208.10 70,000 208.00 207.90 60,000 207.80 207.70 B 50,000 Airspace (level 207.60 below full supply 207.50 level) prior to event 40,000 207.40

207.30 Storage Level (m AHD) Level Storage 207.20 30,000

Release/ Computed Release/ Inflow (ML/d) 207.10 A Major Flood Level 207.00 20,000 Moderate Flood Level 206.90 206.80 10,000 Minor Flood Level 206.70 206.60 0 206.50

12 Jan 6:00 13 Jan 0:0013 Jan 6:00 14 Jan 0:0014 Jan 6:00 15 Jan 0:0015 Jan 6:00 16 Jan 0:0016 Jan 6:00 17 Jan 0:0017 Jan 6:00 12 Jan 12:0012 Jan 18:00 13 Jan 12:0013 Jan 18:00 14 Jan 12:0014 Jan 18:00 15 Jan 12:0015 Jan 18:00 16 Jan 12:0016 Jan 18:00 17 Jan 12:0017 Jan 18:00

Computed Inflow Release Storage Level FSL

Figure 3: Hydrograph for Cairn Curran Operations in January 2011

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

2.3.3 Eppalock Flood Operations

Lake Eppalock is a fixed crest spillway dam and there is limited opportunity for any meaningful pre-release to be made immediately prior to a rain event due to the relatively small capacity of the outlet. The outlet works have a release capacity of approximately 2,000ML/d.

The standing flood operating procedures for Eppalock requires the duty officer to monitor catchment behaviour and report outflows to G-MW management. There is no opportunity for operators to modify the flood outflow through the spillway structure.

Eppalock January Flood

Forecast rainfall and actual rainfall in the Campaspe catchment was similar to that in the Loddon catchment with 98 mm recorded at Eppalock in the 72 hours to 9 am Saturday 15 January. The storage had ceased spilling from previous rain events and releases of approximately 300 ML/d were being made from Eppalock in the days leading up to the January event.

The hydrograph for Eppalock operations during January 2011 is presented in Figure 4. The key features of the operations are summarised as follows.

Section A – experienced two inflow peaks, the first one (102,300 ML/d) occurred at 8 pm on Thursday 13 January (25 hours prior to the peak outflow) and the second at 2 pm on Friday 14 January at a rate of about 137,000 ML/day.

Section B – The peak flow downstream of the storage was recorded 7 hours after the peak inflow at a rate of 80,300 ML/day.

Lake Eppalock is a fixed crest spillway dams and the downstream flows are governed by the level of the storage above the top of the spillway crest. At the peak of the event, the volume of Lake Eppalock rose to 86,000 ML above its nominal operating volume at full supply level (i.e. top of spillway). Through the temporary storage and then gradual release of this water, the peak outflow was about 57,000 ML/d lower than the peak inflow. Campaspe Flows: January 2011 140,000

120,000 A

100,000

80,000 B

Flow(ML/d) 60,000

40,000

20,000

0 Wed 12 Wed 12 Thu 13 Thu 13 Fri 14 Fri 14 Sat 15 Sat 15 Sun 16 Sun 16 Mon 17 Mon 17 Tue 18 Tue 18 Wed 19 00:00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00 Eppalock Computed Inflow Downstream Eppalock Figure 4: Hydrograph for Eppalock Operations in January 2011

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

2.3.4 Channel Flood Operations

Floodwaters in the Loddon and Campaspe catchments began affecting the irrigation channel system on Saturday 15 January as streams broke their banks and overland flow was generated. The channel system had been „shut down‟ ahead of the floodwaters as the full impacts of rainfall were realised. Channels were overtopped in numerous locations across the Rochester and Loddon Valley irrigation areas, and caused substantial damage. A large number of telephone calls were received by G-MW as customers tried to have water diverted away from their property.

The impact of the floods continued for another four weeks as water from the Loddon, Campaspe and Avoca river systems flowed towards the River Murray. Large areas of the Torrumbarry irrigation area were inundated for prolonged periods, and towns such as Kerang and were directly threatened.

The irrigation and drainage channels are not designed as levees, but in several locations they do afford some level of protection for rural landowners and urban townships. During the January 2011 event, G-MW irrigation channel banks were reinforced under direction of the relevant Municipal Emergency Response Coordinator (MERC) to act as levees for the protection of both Kerang and Swan Hill townships.

In some cases channels, drains and “off-stream” storages have been used, under the instruction of the MERC, to divert flood waters.

G-MW operates several small off-stream storages in the Kerang-Swan Hill region. They are primarily filled via irrigation channels connecting the storage to a river delivery system. These storages may also capture runoff from surrounding lands and overland flows from flood paths. The operation of these storages provides an extra source of water during the irrigation season to assist with delivery in high demand periods and also provide extra storage for excess river flows.

During the January event, large overland flows entered the off-stream storages and required G-MW to pass substantial amounts of water from these storages back into natural waterways and in some cases utilise irrigation infrastructure to assist with this transfer. Where there was insufficient storage space to hold this overland flow, the storage was operated to ensure that the least impact on the surrounding public was achieved, that the integrity of the storage was maintained and where possible excess water was directed back to its natural path. All proposals were discussed with the relevant MERC and agreed prior to any action being taken by G-MW.

Off-stream storages that were utilised during this event and required water to be released were , First, Middle and Third Reedy , Little Lake Charm, Lake Charm Racecourse Lake, Kangaroo Lake, and . Of these Kow Swamp was the storage that created the most concern. Any failure of the bank on this storage would have severely impacted the communities of Leitchville and Cohuna and surrounding land to the north of the storage. Releases from the storage were incrementally increased to reduce the possibility of overtopping of the storage and the bank was progressively raised by undertaking major earthworks to provide extra storage/protection. Even with the increased releases and the bank upgrade this storage was operated at levels that had never been achieved before and well above the designed full supply.

Following the peak of the January floods, G-MW utilised the irrigation and drainage channel networks to assist the removal of flood water from properties. This was undertaken with controlled pumping within the capacity of the channel network and where there was

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water no negative impact on downstream customers requiring irrigation or stock and domestic water. The recovery operations were hampered by some areas within the network that were unaffected by floods still requiring deliveries of water for irrigation and stock and domestic needs.

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3 Response to ToR(b) – Levees

The management of levees across Victoria, including ownership, responsibility and maintenance on both public and private land

3.1 G-MW Flood Protection Assets

G-MW is responsible for a small number of levee systems which are operated in conjunction with the irrigation network. These are: - Loch Garry Flood protection district levees, at Bunbartha, near Shepparton - Beattie Depression, south east of Echuca - Little Murray Weir, between Swan Hill and Lake Boga

3.1.1 Loch Garry

The Loch Garry flood protection scheme includes approximately 9 kilometres of levee and a regulating structure. This scheme provides properties within the district protection from floods (up to minor flood level) on the lower Goulburn River. The structure is operated by G-MW in accordance with established operating rules to allow larger floods on the river to enter the floodway. Landowners are notified via SMS in advance of when the structure is to be operated and also informed of the process for the closure of the structure. Landowners within the protected area are charged an annual fee to cover the cost of operating and maintaining this infrastructure.

The lower Goulburn River has approximately 80 to 90 kilometres of levees that have been the subject of much debate for many years. Ownership and responsibility for maintenance of these levees remains unclear.

Loch Garry was operated during the September and November flood events. There were no issues with the operation.

3.1.2 Beattie Depression

The Beattie Depression is a floodplain area that takes overflow from the Deakin drainage system to the Goulburn River and is utilised only when the drainage system is unable to cope with high flows. The floodplain is bounded by levee banks on both sides (18 kilometres in total), and is crown land under the control of G-MW. No private lands are located within the levee system. The primary purpose of the levee system is the confinement of overflows and prevention of inundation of surrounding land.

All operational and ongoing maintenance costs are borne by customers within the Central Goulburn irrigation area.

Only minor flows through the Beattie Depression were experienced during the January event. The floods passed without incident.

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3.1.3 Little Murray Weir

The Little Murray Weir structure, which allows irrigation water to be diverted via gravity through Swan Hill, creates a small storage that supplements water availability for the Torrumbarry irrigation area and is situated on the Little Murray River. This infrastructure has a bank installed to allow the elevation of water for irrigation and this has also provides protection for landowners from flooding. In 1996/97 the height of this bank was increased to provide greater protection against a 1 in 100 year flood event. These works were funded 70% by G-MW. While these banks afford some protection in flood events their primary purpose is for the containment of water for irrigation. Ongoing maintenance costs are borne by Torrumbarry irrigation area customers.

During the January flood this structure operated as expected with no adverse incidents noted.

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4 Response to ToR(c,d & e) – vegetation management in waterways

Waterways management, including the nature and extent of vegetation clearing activities within waterways and their general maintenance;

Identifying those entities and individuals having ownership of waterways and the responsibility for their clearing and their maintenance;

The extent to which, if any, local knowledge of residents is employed in effecting waterways clearing and maintenance.

G-MW facilitates a willow management program in the Mitta Mitta River between and on behalf of the Murray Darling Basin Authority. The program aims to maintain the current channel flow capacity between Dartmouth and Hume by managing invasive willow which grow within the river channel restricting flows.

The Mitta Mitta works are delivered by the North East Catchment Management Authority under contract to G-MW.

G-MW has no active role in managing vegetation in other natural waterways.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

5 Comments and Learnings

5.1 Communications, Consultation and Preparation

Following the rain events in September 2010 and the recovery of water levels in the dams, G-MW endeavoured to inform the community through media of the increased likelihood of flooding now the storages were nearing full capacity.

5.1.1 Flooding of the Loddon House Caravan Park at Baringhup

The region of most concern was downstream of Cairn Curran, and the Loddon House Caravan Park in particular. The Loddon House Caravan Park is situated on the river bank approximately 1 km downstream of Cairn Curran reservoir. The location of the park is well below the nominal statutory planning 1 in 100 year flood level, which makes it vulnerable to the impacts of flooding. The grounds of the park begin to be inundated below the major flood level of R.L. 4.0m, or 21,800 ML/d. The park is on freehold land and G-MW has no role or jurisdiction over the management of the park. The park has been developed to include caravans which have been modified with fixed annexes which prevent them from being relocated in the event of flood or fire risk. Typically caravan parks in similar situations do not have permanent structures below the 1in 100 year flood level.

Over many years, dating back as far as the 1970s, G-MW and its predecessor organisations have maintained routine ongoing contact with the managers of the Loddon House Caravan Park in relation to flood releases from the dam. G-MW recognises that due to the caravan park‟s close proximity to the Cairn Curran spillway, it is possible that the Caravan Park and a number of immediate downstream landowners may not receive timely flood warning through the usual flood warning and emergency response processes which are the responsibility of the Bureau of Meteorology (BoM), Mt Alexander Shire and VICSES.

Approximately 30 years ago, in consultation with the Shire at the time, G-MW‟s predecessors developed a landowner driven telephone based cascade advice system that notified local farmers of storage operations. Typically the messages informed when the storage was nearing Full Supply Level and of an imminent release prior to releases being made. The Loddon House Caravan Park manager has always been included in this cascade telephone system.

This cascade system was recently replaced with a SMS system. During the November 2010 event the new SMS system and the previous telephone cascade system were both in operation to ensure the SMS system operated correctly.

Information regarding the new SMS system was posted on the notice board of the Loddon House Caravan Park and on the counter of the caravan park for patrons and locals who wished to be included on the system.

An article on the new SMS system was also placed in the Baringhup Community Newsletter in October 2010 to inform locals it was available to anyone who was interested. Prior to the November event there were approximately 20 contacts on the SMS system. No patrons of the park elected to have their mobile numbers included in the SMS phone list.

Following the November 2010 flood event G-MW again offered to extend the SMS contact list via an interested and proactive park patron who compiled a list of park patrons‟ phone

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water numbers and contacts to include more than 100 additional SMS contacts. The expanded list was used during the January event.

It should be noted that G-MW is uncomfortable that the caravan park tenants and some of the Baringhup community are now reliant on or have some expectation that G-MW is providing flood warnings. This is not the intent of the SMS messaging system. It is intended to provide operational advice to G-MW customers and landowners who may need to move pumps or stock prior to river flows increasing.

5.1.2 Municipal Flood Plans

G-MW representatives attend each of the Municipal Emergency Management forums within its operating region. The main focus of G-MW‟s involvement in these forums has been Dam Failure emergencies.

Dating back as far as the commencement of the Cairn Curran cascade flood advice system (over 30 years), G-MW and its predecessors have continually engaged in discussion with the then Shire of Newstead, and Maldon Shire, and more recently its successor, Mount Alexander Shire (MAS) in relation to establishing agreed roles and responsibilities for flood events along the between Cairn Curran and Laanecoorie and developing a management plan for the Loddon House Caravan Park.

5.1.3 General Community Expectation

Some in the community have an unreasonable expectation that floods can be prevented or significantly reduced by changing the operating policy of G-MW‟s dams. Pre-releases from a near full storage prior to rainfall events can only provide significant mitigation for minor flood events and must be managed as to not aggravate flooding further downstream. G-MW‟s dams are primarily water storage structures whose operation and maintenance is funded by water entitlement holders. G-MW must balance the obligation to store the maximum possible resources to supply water entitlement holders with the risk associated with forfeiting stored resource for flood mitigation purposes.

There is also a strong community perception that G-MW can reduce the impact of flooding by operating the irrigation network to divert water and therefore reduce the impact on landowners. This misconception is based on the assumption that irrigation channels are the same capacity from offtake to outfall (top to bottom) and that G-MW can dispose of the excess water to another location. As a distribution network, irrigation channels progressively decrease in capacity as they extend downstream in the system and usually outfall to a drainage channel or a natural waterway. The drainage channels and waterways are usually operating at full capacity or above in flood events and transferring any water to these locations would only increase the flooding at the outfall point.

Operating the irrigation system in this manner is not only impractical, but could also lead to potential litigation against G-MW.

Many landowners believe that G-MW irrigation channels and drains also act as levee banks. As previously stated, whilst these assets can afford a small amount of protection in some locations they are neither designed nor constructed to act as a levee bank.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

5.2 Outcomes of G-MW Debriefs and Reviews

G-MW conducted internal debriefs after each flood event in 2010/11. The findings from the debriefs were: The operating procedures were followed appropriately and remain satisfactory for the safe operation of the assets. The November and January floods in the Loddon and Campaspe catchments were rare (likely to be rarer than a 1 in 100 year annual recurrence interval) and that the operating procedures had never been used in such events.

G-MW is undertaking an independent review of the dams operating procedures and the use of those procedures during the November and January events. The review is scheduled for completion in October.

The forecast information from BoM was consistent with similar information provided in previous flood events. The flood level scenario modelling provided by the BoM was helpful to gauge the possible severity of the event. Some improvements could be made to streamline internal and external communications. Following the November event, a general Situation Report covering the operating status of all G-MW dams was developed. The Situation Report is now used to provide general updates to all key internal (management and operational roles) and external (VICSES, BoM, DSE) stakeholders during flood events. Feedback from DSE and VICSES is that the Situation Report is informative and useful. The current level of personnel resourcing of dams operations is adequate to manage significant flood events. 24hr operating flood rosters were implemented during each event. There was some difficulty in getting staff to roster off to rest, but generally staff were able to get adequate rest breaks. During the September and November events, staff were isolated at William Hovell and Buffalo dams. This was expected and planned for at the time. Following the peak of each event there was significant public interest at the storages, which presented some issues with public and traffic management. Coordination and communication with the Regional Incident Control Centres (ICC) was adequate and was maintained through the regular situation reports and periodic telephone calls. In future events G-MW will offer to place a liaison officer in the ICC. Engaging with public to increase awareness of the possibility of flooding was difficult prior to the November event. This may be due to the long period of drought prior to these floods and the consequent decreased awareness of flooding. G-MW‟s experience at Cairn Curran is that there was very little awareness or receptiveness of flooding within the newer members of the community prior to the November flood. Following that event there was significant interest. In the irrigation areas the public were continually requesting updates from G-MW on flood issues that were unrelated to the operation of G-MW infrastructure. There were also increased requests from landowners for G-MW to operate irrigation infrastructure to divert flood water and this caused difficulty for staff and customers. There is a clear need to reinforce the roles of the various agencies in relation to flood warnings and updates and to disseminate this information publicly.

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Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Appendix A. – Parliamentary Public Works Committee Reports

Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Appendix B. – Board Policy on Flooding

Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Appendix C. – Presentation to Open Public Hearing

Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Appendix D. – Hansard Transcript of Presentation to Open Public Hearing

Submission to the Inquiry into Flood Mitigation Infrastructure in Victoria 2011 Goulburn-Murray Water

Appendix E. – Loddon and Campaspe Bulk Entitlement Orders