Levees

Lower Murray Reclaimed Irrigation Area (LMRIA) levee banks

The Government of South Australia maintains a number of agricultural levee banks along the Lower Murray, between Mannum and Wellington. Agricultural levees in the Lower Murray were constructed to contain water within the main river channel, to reclaim land for agricultural activity and to house irrigation infrastructure. While these levees provide some flood protection by withstanding flows equivalent to those experienced during the 1974 flood, it is not their primary purpose, and they can only perform their role up to their design level, above which, they are likely to overtop.

The Department for Environment and Water (DEW) is currently undertaking assessments of all government owned levees to determine the extent of damages and investigate safe access methods for stabilisation works.

The assessment and stabilisation process will be undertaken in 3 stages:

• Stage 1
Drones will be used to capture images and film of levee conditions, and height survey data will be captured utilising drone based LiDAR (light detection and ranging) technology. LiDAR surveys commenced at the end of February 2023 and base stations have been setup at each location.

• Stage 2
Once it is deemed safe to do so, DEW will access levees by foot or light vehicle to undertake on-ground inspections and undertake geophysical testing, where able, to ensure stability of banks for civil earth moving equipment. Methodology for any stabilisation works required will then be finalised.

• Stage 3
Stabilisation works will be undertaken as necessary to ensure separation from the River under normal operational conditions, to assist with the pumping of water from those inundated areas.

Council and private levees:

While the Government of South Australia does not generally have a role in ensuring private or council-owned levees are maintained, it recognises the need to get all the inundated agricultural land dewatered as soon as possible and will undertake the same process for all levees, whether they be private or government owned.

Opportunities to partner with councils and private landholders and access funds to improve or upgrade levee banks where the need is identified, will also be explored.For comments on the operation of levee banks in an emergency flood situation, please contact the SES.

Physical inspections of damaged levees will be undertaken once it has been deemed safe to do so. It is not possible to predict what works will be required, or when they will be completed, until such time these inspections have been undertaken. Considerations for works to be undertaken include the safety of our staff and contractors, accessibility (both to and along the levees), integrity of the remaining length of levee and availability of contractors and materials.

What's being done?

DEW has been onsite at levee locations since the start of March 2023, working with contractors and local government to determine safe access routes, which will allow structural integrity testing to begin.

Once the levee banks have been assessed for stability and bearing capacity, and deemed safe, short-term stabilisation solutions will be undertaken to enable the dewatering of the land and to provide farmers access back onto the agricultural land.

DEW is currently working with landowners and irrigators to discuss longer term solutions for the agricultural levees. Once the areas have dried out and the levees are no longer engaged on both sides, a full condition assessment will be undertaken to determine longer term requirements.

Each levee is likely to have different possible options, and there is unlikely to be a one-size-fits-all solution. It is not possible to confirm what works will be required, or when they will be completed, until the levee inspections and assessments are finalised.

Primary producers impacted by the River Murray flood are encouraged to access the Primary Producer Recovery Grants and the Primary Production Irrigation Grants along with other services.

For more information visit www.pir.sa.gov.au.

Earthen Levee Embankment Inspection and Repair Guide

An 'Earthen Levee Embankment Inspection and Repair Guide’ has been developed to assist councils and landholders with the inspection and repair of levee embankments.

It is not intended to replace expert advice and it is recommended that landowners obtain advice from an experienced levee embankment or dam engineer, or other relevant expert.