Levee Bank Flood Protection 

Updated August 2020

Construction to raise the Wagga Wagga Murrumbidgee River Main City levee system was completed in March 2020, giving residents south of the Murrumbidgee a 1 in 100-year level of protection against flooding for the first time. The Main City Levee provides protection for the central business district, essential city assets and thousands of residential homes.

Wagga Wagga City Council began the Main City Levee upgrade in 2017 through a staged construction. The Main City Levee extends from Flowerdale to Kooringal Road Monumental Cemetery and incorporates cycle and pedestrian pathways which also forms part of the City’s Active Travel Plan.

Committee for Wagga looks forward to working with both the insurance industry and Wagga Wagga City Council in assessing the effect of increased flood protection on insurance premiums for both residence and businesses within the CBD area. This process is awaiting the adoption of the Wagga Wagga Overland Flow Flood Risk Management Study and Plan 2019 by Council. The report will facilitate the provision of necessary data to the Insurance Council of Australia.

North Wagga Wagga Flood Plain Mitigation:

The Wagga Wagga Revised Murrumbidgee River Floodplain Risk Management Study and Plan (FRMSP) considered a range of flood mitigation options for the North Wagga Wagga community and endorsed the following recommendations:-

• Undertake a feasibility study investigating upgrading the North Wagga Wagga levee to a 5% annual exceedance probability (AEP) level of protection (1 in 20-year protection), with an equivalent upgrade to Hampden Avenue

• Undertake a feasibility study investigating voluntary house raising and voluntary purchase scheme which encompasses residential properties in North Wagga Wagga and on the wider floodplain

The NSW Government provided a grant of $156,000 to support a feasibility study to determine which of the above options for the North Wagga Wagga community is more viable in terms of reducing flood risk exposure on the Wagga Wagga floodplain. Feasibility studies have commenced in relation to the first option, to upgrade the North Wagga Wagga levee to a 5% AEP level of flood protection.

North Wagga Wagga community representatives have expressed concerns that the FRMSP did not properly consider the range of the flood mitigation options that might be pursued in North Wagga Wagga, in particular that a flood protection levee to protect the North Wagga Wagga community from a flood event greater than 5% AEP was not recommended in the study and that this conclusion was wrong.

In response, the Wagga Wagga City Council’s Floodplain Risk Management Advisory Committee resolved to commission an independent peer review of the North Wagga Wagga component of the overall FRMSP. This review will consider the procedure and analysis undertaken in completion of the FRMSP and determine if it is reasonable that a flood protection levee protecting North Wagga Wagga from an event greater than a 5% AEP flood should be considered in the feasibility study process currently being undertaken. The Wagga Wagga City Council is yet to appoint a consultant to undertake this review.

For updates follow the link to the Wagga Wagga City Council Projects page:

Wagga Wagga City Council Projects - Levee Upgrade

Funding

The following funding contributions have been made to cover the $23M cost of the Wagga Wagga levee upgrades:

• City of Wagga Wagga - raising one-third share of $7.75M through a special rate variation, effective from 2016 and maintained for five years

• State Government - Stage 1 grant funding of $2M and Stage 2 grant funding of $2.1M

• Federal Government - $10M funding under the Community Development Grants Program

Background

Stage 1 of the Main City Levee Upgrade commenced in 2017 and was completed in January 2019. Stage 1 consisted of 2 sections; Section 1 from Flowerdale, including the spillway, to Gobbagombalin Bridge, and Section 2 from Copland Street, including the spillway, to Kooringal Road Monumental Cemetery.

Stage 2 of the Main City Levee Upgrade commenced in January 2019 and was  completed in April 2020. This section extends from Gobbagombalin Bridge to the Cadell Place wall (parallel to Fitzmaurice Street) to Johnston Street and then from Riverina Playhouse to Copland Street.

The levee bank flood protection system is the city’s single most important piece of infrastructure, safeguarding central Wagga Wagga and the central business area from the effects of flooding. The localised effects of a flood breaching the levee bank would be devastating and displace approximately 7,000 people however the broader reaching impacts on the regional economy would have negative flow on effects at a national level. Wagga Wagga’s immediate population is greater than 65,000 however the city is the goods and services hub for over 185,000 people, emphasising the strategic importance of the city to a regional population.

In the event of a flood breaching the levee up to 2,600 homes and 1,100 businesses will be inundated, the majority severely flooded. In addition, the Sturt Highway connecting Sydney with Adelaide will be closed and likely to be severely water damaged.

The previous flood protection system was predominantly an earthen levee and initially constructed in 1956 following frequent flooding events. The levee has since been upgraded to a level that was considered capable of resisting a 1 in 100-year flood event, the equivalent of a river height to 11.49 metres. However, modelling of the system’s capacity and observations during flood events in 2010 and 2012 revealed the system is not capable of resisting a 1 in 100-year flood and would only protect the city from a 1 in 60-year flood event.

Without adequate protection against inevitable flood events, the community is exposed to a high degree of risk and ultimately devastation if the levee fails. In addition, the community experiences unrelenting negative perceptions and realities relating to business confidence, insurance premiums and property values. 

The insurance premiums of the city’s residents and business owners will continue to rise annually to reflect significant risk to flooding and the investment potential of property in the CBD reduced until the levee bank is upgraded and the risk mitigated. 

As an example, following severe flooding to Roma in 2010, 2011, 2012 insurance companies refused to offer new policies and the town was considered uninsurable. Following the upgrade of the town’s levee bank system in 2013 insurance premiums have again been made available, reduced by an average of 45% and in some cases up to 90%. 

Flooding to the city will inundate up to 2,600 homes and 1,100 businesses, displacing over 7,000 people.