Public Works Committee: Intermediate Remediation of the Lower Murray Reclaimed Irrigation Area Levees

Mr BROWN (Florey) (11:50): I move:

That the 70^th report of the committee, entitled Intermediate Remediation of the Lower Murray Reclaimed Irrigation Area Levees, be noted.

The Department for Environment and Water (DEW) proposed to deliver intermediate, non-engineered remediation works to damaged sections of government and privately owned levees in the Lower Murray reclaimed irrigation area. This is the second of four stages of the Lower Murray Reclaimed Irrigation Area Levee Remediation and Resilience Program, which is part of the South Australian government's recovery response to the 2022-23 River Murray floods.

The Lower Murray reclaimed irrigation area is located between Mannum and Wellington and consists of 27 unique areas, protected by approximately 107 kilometres of agricultural levees. These serve as flood mitigation for essential infrastructure assets and play an important role in providing water security and environmental protection.

DEW maintains 10 of the 27 levees, which account for approximately 67 kilometres of the levee infrastructure. These levees are maintained to withstand water levels at least equivalent to those observed during the flood event of 1974. In addition to the government-owned levees, the remaining 17 levees account for a further 40 kilometres, which are privately owned. These are the responsibility of landowners and irrigation trusts.

Between November 2022 and February 2023, the River Murray experienced a flood event due to heavy rain and flooding interstate. The third highest flood ever recorded in South Australia, this flood event had a significant impact, with an unprecedented number of homes, shacks, businesses and infrastructure affected. As a result, 20 of the 27 levees were overtopped or breached, causing damage to the levees and inundating large areas of agricultural land. Of the 20 damaged levees, eight were owned by the government and 12 were in private hands.

In response, the South Australian government undertook short-term flood relief and recovery efforts, which included immediate stabilisation works and dewatering across the levee network. This was to enable landholders to access their land and recommence agricultural production and was stage 1 of the Lower Murray Reclaimed Irrigation Area Levee Remediation and Resilience Program.

This project represents stage 2 of this program. Its key aim is to mitigate flooding to the Lower Murray reclaimed irrigation area's agricultural lands and its essential infrastructure assets that are protected by the levees. These assets include water and power supply, wastewater and transport routes. The project is an interim measure against future high-flow events until longer term engineered approaches can be fully considered and realised.

Additionally, the mitigation of flooding of the area's agricultural lands will provide primary producers with the confidence to fully return to agricultural production. The project's intermediate remediation strategy will undertake an earthworks regime to temporarily repair damaged levee banks to remediate crest levels to their pre-flood level. These works will utilise or build upon existing levees where possible and will often require keying in the newly constructed levee into an existing one.

All works will be performed under supervision of a suitably qualified geotechnical engineer. These works are a measure against future floods or high-flow events in the short to medium term, where there is the potential for future damage to the levees and possible inundation. Therefore, these flood mitigation measures will avoid costs to government, businesses and communities that could be impacted by flooding and inundation of agricultural land. In doing this, the project also contributes to the building of a more resilient region.

The total estimated cost of the intermediate remediation works is $27.7 million. This builds on the set $3.7 million expenditure for the immediate stabilisation works carried out 2023. The department notes that work cannot be performed during the winter months because of the effects the wet weather has on clay soil, therefore construction is expected to take place over a 24-month time frame. Preparation works have commenced, including the testing of materials from quarry pits to determine suitability, with practical completion expected in June 2026.

Alongside the intermediate repair of the damaged levees, the project will also provide social, economic and environmental benefits. It will contribute to the protection of South Australia's drinking water through safeguarding SA Water infrastructure, including the Murray Bridge-Onkaparinga pipeline that supports the provision of drinking water for metropolitan Adelaide. It will contribute to ensuring the health of downstream aquatic environments, including assisting in the management of environmental water.

This project will minimise impacts to the Coorong and Lakes Alexandrina and Albert Ramsar site, through containing the River Murray within its main channel, preventing up to 70 gigalitres of additional evaporative losses each year, especially in a drying climate. It will provide public access to government-owned levees for recreational activities and opportunities for regional employment. Lastly, it will strengthen relationships between DEW and various stakeholders, including landholders, irrigation trusts, the Ngarrindjeri Aboriginal Corporation, and First Peoples of the River Murray and Mallee Region.

The works will be managed in accordance with the department's project management framework. The Department for Infrastructure and Transport will manage and implement the construction components, while DEW will have overarching coordination and management responsibility, including governance, communications, stakeholder engagement and management of the necessary approvals.

A coordinated systematic approach to identifying risks in accordance with the department's risk management policy and procedure will be implemented. Geotechnical investigations will be conducted and the best available technology will be used to ensure that the levee banks are adequately stabilised. To mitigate against weather-related delays, contingency plans will be developed, as well as the close monitoring of weather patterns, the establishment of buffer times in the program time line and work being conducted on several levees concurrently.

Safety risks for workers will be minimised by the creation of a comprehensive safety management plan and regular safety checks. To lessen environmental impacts, environmental management plans will be developed, encompassing erosion control measures, conditions for water-affecting activities, and the monitoring and management of construction site run-off. The budget and time line will be regularly monitored to minimise cost overruns.

An ecologically sustainable development report has been prepared by the department, outlining the sustainable objectives, principles and actions for the project. These include: work conducted within the footprint of the levees to minimise vegetation impact; work undertaken during business hours to limit noise impact on fauna; locally sourced and recycled materials used where possible; the development of a soil erosion and drainage management plan; and the use of non-potable and transported water, where possible, to avoid use of the River Murray water supply.

The levees are within the Ngarrindjeri and Others Native Title Determination (Part A) area and are subject to the Ngarrindjeri and Others Native Title Settlement (Part A) Indigenous Land Use Agreement, and the First Peoples of the River Murray and Mallee Region native title claim area. The department has initiated engagement with the traditional owners to ensure their views and priorities are included in the works going forward. Cultural heritage surveys will be completed to ensure compliance under the Aboriginal Heritage Act and a cultural heritage management plan will be developed, informed by the Aboriginal heritage database and cultural heritage surveys undertaken by traditional owners. To manage cultural heritage impacts, cultural heritage monitors will be on site for the duration of any ground disturbance works.

The project is not likely to impact any commonwealth or state non-Aboriginal heritage places. However, if heritage places are identified, works will not commence until heritage management plans are developed. As the Lower Murray reclaimed irrigation area community has been significantly affected by the 2022-23 floods, early and effective ongoing community engagement is necessary, particularly in managing community expectations surrounding the intermediate remediation works and how these will differ from the proposed longer term engineered repairs.

Key stakeholders, such as individual landholders, irrigation trusts, local councils and industry groups, will be consulted. Tailored communication and engagement plans will be developed in consultation with Ngarrindjeri and the First Peoples of the River Murray and Mallee Region to meet their needs.

The committee has examined written and oral evidence in relation to the intermediate remediation of the Lower Murray reclaimed irrigation area levees. Witnesses who appeared before the committee were: Sue Hutchings, Acting Executive Director, Water and River Murray Division, Department for Environment and Water, and Brendan Cowie, Acting Manager, Levee Recovery, Department for Environment and Water. I thank the witnesses for their time. I would also like to thank the member for Hammond for his statement to the committee regarding the project in his electorate.

Based upon the evidence considered, and pursuant to section 12C of the Parliamentary Committees Act 1991, the Public Works Committee reports to parliament that it recommends the proposed public work.

Mr PEDERICK (Hammond) (11:59): In the milliseconds I have left, I certainly support this work. I am disappointed that it has taken 18 months and we are only up to the second stage of the remediation works of the River Murray levees. However, it is welcomed by the community, and I hope that there is appropriate consultation with the community so that locally sourced items are used, including clay. That is a much needed measure to make sure that we do this in a cost-appropriate manner to get the best results for both stakeholders in the region and farmers. They have been frustrated by the time it has taken to get to this stage, but they do welcome this funding. I wish this project all speed.

Motion carried.