Figure 1 – Port Phillip and Westernport Region

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Figure 2 shows the waterways and drainage assets managed by Water within the Region.

Figure 2 – Melbourne Water’s waterways and drainage system

How is Melbourne Water funded to undertake Waterways and Drainage Services?

Melbourne Water’s Waterways Group manages rivers and creeks and major drainage systems throughout the Port Phillip and Westernport region. The Group’s activities are funded via a Waterways and Drainage Charge which is levied on customers in the region. The charge appears on customer’s water bills and is collected by seven water retailers within the region on our behalf from around 1.8 million property owners across the region.

The Essential Services Commission (ESC) regulates Melbourne Water’s prices for waterways and drainage services and endorses the service commitments. The Waterways Operating Charter supports pricing submissions to the ESC.

Every five years, Melbourne Water must submit a Water Plan to the ESC outlining what activities we propose to undertake to manage waterways and drainage services across the region and the cost associated with this. The ESC then reviews the proposed programs and provides a determination on what price will be set for the five year period.

There is a Waterways and Drainage charge for properties within the urban growth boundary and a Waterways (only) charge for properties outside the urban growth boundary UGB). Figure 3 shows the extent of the current urban growth boundary. This arrangement reflects the different level of services provided to urban and rural 5

communities. Properties outside the UGB are considered rural and will receive a charge for waterways services only. Properties within the UGB generally benefit from our drainage and flood protection services as well as waterway management services. Most of the significant pipe and channel drainage systems benefit properties with the UGB.

Figure 3 – Port Phillip and Westernport Region – Urban Growth Boundary

An exception to the above charging arrangements is the two special precept areas where charges are based on specific levels of service – Patterson Lakes Precept Area and – Longwarry Flood Protection District (KWRLFPD). Further details of the KWRLFPD arrangements will be provided later on in this submission, as it is in affect a rural drainage scheme.

Funding for the five-year period from 2008/09 to 2012/13 totals some $844 million. This is allocated to the following key activities:

 $11.6 million - community and stakeholder  $1751 million – managing waterway improvement  $9.8 million – managing environmental flows  $87.32 million – managing water quality  $179.63 million – flood and drainage management  $380.54 million – managing urban growth

1 Includes funding for monitoring, investigations and research projects and some waterways community projects such as stream frontage management grants 2 Includes funding for monitoring, investigations and research projects 3 Includes funding for monitoring, investigations and research projects 4 Mainly funded by development industry rather than through waterways and drainage charge 6

Waterways and Drainage Services Provided in the Region

Throughout the region Melbourne Water has adopted a holistic approach to the delivery of our waterway, drainage and floodplain management services. The services include:

 Protecting the ecological health and amenity of waterways  Helping achieve water quality objectives  Responding to pollution and blue-green algae outbreaks on waterways and water bodies  Planning and delivery of environmental water entitlements  Managing water diversions from rivers and creeks  Issuing stormwater licences for extraction from drainage systems  Operating a flood monitoring network on major rivers and creeks  Monitoring, investigating and researching particular issues to support our decisions and the delivery of our programs  Educating and engaging our customers and the community in the work we do  Providing, managing and/or maintaining structures that control the path, quantity and quality of stormwater, such as constructed wetlands and new drainage infrastructure to service urban development.

Key strategies that currently guide our investment priorities across the region are the Regional River Health Strategy, Waterways Water Quality Strategy and the Flood Management and Drainage Strategy.

Drainage and Floodplain Management within the Region

We are generally responsible for managing major drainage systems that carry stormwater to waterways and bays and have catchment areas greater than 60 hectares. Drainage in catchments smaller than 60 hectares is generally managed by local councils. However other organisations such as road and rail authorities do have responsibility for management of some stormwater assets.

Floods are natural events that benefit some ecosystems but can also negatively affect people and property. Flood risks and impacts to people and property are managed through three key activities – prevention, response and recovery – delivered collaboratively by several agencies with flood management responsibilities.

Specific services provided by Melbourne Water throughout the region include:

 Investigations to understand the nature and extent of flooding and floodplains  Flood mitigation works program to reduce the risks associated with flood events  Operating a network of rainfall and river level stations to provide a flood prediction service for major rivers and creeks within the region  Working with others through partnerships to build their capacity and educate the community in regard to flood risk  Maintenance and renewal of the extensive network of built and natural drainage and waterways assets  Maintenance and renewal of the built assets in the Precept Areas.

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Figure 4 shows the Region which has a heavily urbanised central core with an extensive rural component elsewhere. The figure also shows the abutting Catchment Management Authorities.

Figure 4 - Port Phillip and Westernport Region, Urban and Rural areas

Koo Wee Rup – Longwarry Flood Protection District; Background / History

For a more detailed history of the Koo Wee Rup swamp in terms of drainage and agricultural production please refer to the book ‘From Swampland to Farmland – A History of the Koo Wee Rup Flood Protection District’ by David Roberts. The book with its maps, diagrams and photographs explains the formation of the former swamp and describes the efforts and problems associated with its drainage as well as the development of the area as a farming district.

The Koo Wee Rup – Longwarry Flood Protection District (KWRLFPD) lies in what was originally known as the Koo Wee Rup Swamp. In the 1800s the Koo Wee Rup swamp extended over an area of some 40,000 hectares. It was covered by dense stands of swamp paperbark, reeds and bullrushes and provided a natural barrier between Melbourne and West Gippsland. The swamp was fed by a catchment of 220,800 hectares in area that included three major drainage basins of , Bunyip River and Lang Lang River catchments.

Figure 5 below shows the extent of the KWRLFPD along with the major rivers, creeks and constructed drains.

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Figure 5 – Koo Wee Rup – Longwarry Flood Protection District

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Prior to European settlement, the Yallock Creek formed the only permanent outlet from the swamp into . In the late 1800s and early 1900s the swamp was slowly drained by the construction of over 500 kilometres of major and minor channels to convey stream flows from upstream catchments and local runoff through the swamp to Western Port.

The district has a long history of flooding from the early years of the drainage works with major flooding occurring in April 1901, June 1911, October 1923, August 1924, December 1934, April 1935 and October 1937.

The December 1934 flood resulted in flows never seen before or since with great loss of property and stock. Over 1000 people were made homeless and the Koo Wee Rup hotel had almost two metres of water in it. A Royal Commission was established in 1936 that noted the deficiencies in the drainage system and recommended that substantial improvements be made. The works involved alternations (eg levee construction, sediment removal) and extensions to main drains.

As part of the improvements recommended by the Royal Commission construction of the Yallock Outfall was undertaken in the 1950s. The Outfall splits the flow of the Bunyip Main Drain at Cora Lynn. The completion of the spillway at Cora Lynn in 1962 was done to divert floodwaters into the Yallock Outfall and so protect the township of Koo Wee Rup. The spillway was the last major work to take place in the KWRLFPD until the Bunyip Main Drain rehabilitation works commenced in 2001 with the last stage of these works currently being constructed. The intent of these works is to renew the levee banks and increase the flow carrying capacity of the main drain to a 15 year ARI event.

Flooding in the district results from not only over topping of the main carrier levees but also as a result of floodwaters from the local catchments exceeding the capacity of the local drainage system.

Flooding within the district is characterised by large areas of water pondage, particularly behind raised roads and levees. Due to the extremely flat nature of the terrain, even relatively minor events can inundate large areas within the district.

KWRLFPD Management Arrangements

The floods of 1911 severely impacted the lives of many settlers, which caused much discontent between them and the Public Works Department (PWD) who managed the district at that time. As a result of several local meetings a list of proposed works to improve the drainage in the district was developed.

The PWD argued that the Government could not pay for the suggested improvements and had never guaranteed protection against ‘extraordinary’ floods. If the settlers wanted their suggested works undertaken they would have to pay for them themselves. The PWD did not have the powers to charge the settlers an annual rate, as their contribution to paying the total cost for new improvements that were necessary.

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The State Rivers and Water Supply Commission (SRWSC), which was formed in 1905, was the only Government body with rating powers and so administration and responsibility for the Koo Wee Rup Swamp drainage scheme (known today as the KWRLFPD) was transferred to it at the end of 1912.

The SRWSC, renamed the Rural Water Commission, continued to manage the district until November 1989 when the Dandenong Valley Authority (DVA) expanded its area of responsibility following a lengthy consultation and engagement exercise with affected communities and councils. The renamed Dandenong Valley and Western Port Authority (DVWPA) was merged with the Melbourne and Metropolitan Board of Works and other authorities in 1991 to become Melbourne Water. Melbourne Water is still the regional drainage and floodplain management authority for the district.

KWRLFPD – Funding and Services

Properties within the KWRFPD do not pay the waterways and drainage charge as do other property owners with the Port Phillip and Westernport region. They pay an exclusive rate (precept charge) that reflects the higher levels of drainage service provided in the area.

Melbourne Water’s drainage and flood protection services in the area include maintaining local and main carrier drains, culverts, floodgate structures, occupational bridges, fences and flood warning systems to a design flood event. Key waterway management activities include:

 Desilting  Vegetation control  Erosion control  Bridge and structures maintenance  Debris removal  Repairs

The two main carrier drains (Cardinia Outfall Drain and Bunyip Main Drain) will take flows from a storm event of an intensity experienced once every 7 years in some locations and 15 years in other locations. Local drains may flood more frequently.

This level of service compares with other rural, flat lands where typically the main drainage systems on floodplains are capable of only carrying flows with a 1 or 2 year average recurrence interval prior to exceeding their banks and spilling onto the floodplain.

KWRLFPD Advisory Committee

Due to the unique requirements of the district, a local representative advisory committee consulting on service levels and charging arrangements were established under the various acts appropriate at the time. Melbourne Water currently operates under the Water Act 1989 and continues to consult with the customer committee under its general provisions.

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Regular meetings are held (on average every two months) to provide a forum for monitoring activities undertaken in the district and to discuss future service requirements. Charges are discussed on an annual basis before they are submitted to Melbourne Water’s Board for approval and subsequently to the Essential Services Commission.

KWRLFPD – February 2011 Rainfall Event

A major storm event occurred over the district and its contributing catchments between the 4 and 6 February 2011. Work undertaken by a consultant on Melbourne Water’s behalf found that:

 Rainfall totals in excess of the 200 year ARI were recorded in some district catchments, with rainfall totals above 120mm being experienced in multiple locations  The storm event was variable across the contributing catchments due to spatial and temporal distributions  Recorded flows in Deep Creek and Eumemmering Creek were in excess of the 100 year ARI. For Toomuc and Cardinia Creeks, flow rates in excess of the 200 year ARI were estimated. In the Bunyip River flows were estimated at approximately equivalent to an 18 year ARI event.

Flooding within the district was wide spread as would be expected given the amount of rainfall during the event. Figure 6 shows the extent of flooding from the February 2011 storm event as modelled by the consultant.

Figure 6 – February 2011 Extent of Flooding (Cardno 2011)

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KWRLFPD – June 2012 Rainfall Event

Although the actual rainfall totals for the event on the 21 and 22 June were not that large from a rainfall total or intensity perspective they did result in significant areas of flooding in the district, which was well in excess of what would be expected. Rainfall totals and intensities at many locations were such that runoff in the order of a 1 or 2 year ARI would have been expected.

The higher than expected runoff volumes and the time that the drains flowed at high depths limited the ability of the adjoining land to drain to the carrier drains and is attributed to an exceptionally wet catchment as discussed below.

For Koo Wee Rup, the annual rainfall for 2010 was 18% above the long-term annual average, and for 2011 it was 16% above the average. For 2012 up until the end of May, rainfall was 44 % higher than the annual average to then, and in June the average monthly rainfall had already fallen by 9am on the 21 June. So it is reasonable to assume that the catchment was thoroughly soaked.

During flood modelling it is assumed that during a rain event some of the initial rainfall seeps into the ground and that after this initial rainfall loss is satisfied stormwater runoff will commence. After this initial loss is satisfied some rainfall will generally continue to soak into the ground on an ongoing basis and is called the ongoing loss. Typically this ongoing loss is estimated at 2.5 mm per hour.

For this event if we assume that the catchment was totally saturated and no ongoing loss took place then the recorded rainfall intensities of around 2.6 mm per hour effectively doubles to 5.1 mm per hour. This increased rainfall intensity effectively becomes something that could have generated flows in the order of 40 to 50 year ARI.

Thus from a relatively small rainfall event a significant flood event occurred.

KWRLFPD - Melbourne Water Response to Community Concerns

The June 2012 event had significant impact on the farming community in the district. This community voiced significant concerns to councils, politicians, media and Melbourne Water. Their main concern was that water was unable to drain from their paddocks into the carrier drains and this had impacted crop production.

In response Melbourne Water is fast-tracking a package of works to help ensure that the district is better protected from floods.

Extra crews were mobilised to deliver the first round of work in August and September 2012. Consultation with the community about longer-term projects is continuing as we seek to accelerate the approvals for these works where we can.

These additional works are part of our broader efforts to improve the capacity of the district’s drainage system. Melbourne Water spends $1.2 million annually to maintain the district’s drains and funds major projects like the $3 million repairs to Bunyip Main Drain Road (North), which were completed in May 2012 (following a drain bank slip caused during the February 2011 flood event). A multi-million dollar reconstruction of the Bunyip Main Drain between 11 and 13 Mile Roads in Vervale is also underway. When the reconstruction works are completed the Bunyip Main Drain will be able to carry a flow event with a 15 year ARI.

The KWRLFPD is low lying and former swampland which means it is susceptible to flooding. A number of areas also have a high conservation value including providing wildlife corridors for the Southern Brown Bandicoot or habitat for Australian Grayling.

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These conservation values cause considerable tension with the local farming community who see the main value of the districts drains as providing drainage values. Equally other sectors of the community see these conservation values as being of prime importance. To address these competing concerns we are working with state and federal departments to find a more strategic long-term solution.

We will never completely eliminate the risk of flooding in the area however we can improve the resilience of the district and ensure that residents and growers are better protected in the future.

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