What do the proposed upgrades involve?

The scope of the upgrade involves widening the levee banks to increase the drain’s capacity and improve the structural integrity of the banks, which were originally built with old technology in the 1920's. It also involves building a spillway structure at the Southern end of the drain in Bovell which will receive any overflow from the drain and divert it to the Lower Vasse River. 

What are the benefits of the project?

The Vasse Diversion Drain is essential to protect Busselton from flooding. This project will ensure the drain is able to handle up to 1 in 100 year rainfall events and protect property and the surrounding environment from flooding. At the completion of the project, the drain will be able to hold more water, move more water and the banks will be stronger to ensure the water is contained.

Why does the drain need to be upgraded now?

Despite recent improvements, Busselton’s current drainage system does not protect the area against a 1 in 100 year rainfall event. Since the original construction of the drain, large residential areas have been developed alongside the drain, causing less open soil that can hold water (after rain) and increased run-off. These conditions increase the risk of flooding.

What is a 1 in 100 year rainfall event?

The phrase “1 in 100 year event” refers to the estimated probability of an event happening in any given year. A 100 year event has a 1 percent chance (1 in 100 chance) of occurring in any given year. Therefore, this does not mean this kind of rainfall will occur every 100 years, or that it can only occur once in 100 years. However, it helps us place a particular weather event in the context of similar events.

Busselton, being very flat, is particularly prone to flooding and has experienced such events in 1963, 1964, 1965, 1986, 1997 and 1999.

What environmental considerations is the project team addressing?

This project requires a small amount of tree clearing along the drain to allow us to make the drain wider. We have been working with Department of Water and Environmental Regulation and other flora and fauna experts to assess and mitigate any impacts to threatened species in the area, such as: 

·  Pseudocheirus occidentalis (Western Ringtail Possum) – Vulnerable (Federal and State)

·  Calyptorhynchus baudinii (Baudin’s Cockatoo) – Vulnerable (Federal and State)

·  Calyptorhynchus latirostri (Carnaby’s Black Cockatoo) – Endangered (Federal and State)

·  Calyptorhynchus banksia naso (Forest Red-tailed Black Cockatoo) – Vulnerable (Federal and State)

·  Caladenia procera (Carbunup King Spider Orchid) – Critically Endangered (Federal and State)

·  Westralunio carteri (Carter’s Freshwater Mussel) – Vulnerable (State)

Various management plans to protect local populations are being developed for the project. 

This project is currently seeking environmental approvals through our regulators.

Who are the Busselton Flood Management Steering Committee?

Now dissolved, the Busselton Flood Management Steering Committee was formed in 1997 following a major flood event in Busselton. It comprised representatives from (the then) Office of Water Regulation (now Department of Water and Environmental Regulation)(DWER), Department of Agriculture (now Department of Primary Industries and Regional Development), Department of Conservation and Land Management (now Department of Biodiversity, Conservation and Attractions)(DBCA), Water and Rivers Commission (now merged with DWER), GeoCatch, Shire (now City) of Busselton and Water Corporation.