Where the Wirribi Yaluk/Werribee River meets Nerm/Port Phillip Bay, the estuary mouth changes shape and depth over time as sand drifts along the shore from nearby beaches. To ensure safe boating access to the river, Parks Victoria, who are responsible for maintaining this area of the river, conduct dredging operations as required. This usually takes place every 12-18 months, and has been occurring for the past 20 years. Sand buildup around the boat ramp and jetty may also be relocated to permit safe access to these facilities.
The depth of the river channel is monitored to determine when dredging needs to be undertaken. The rate of sediment and sand moving around is cyclic but can vary year to year. Sand that is dredged out of the channel is deposited on the shore to replenish the beach profile or shoreline, depending on where it is needed. Sometimes this sand can have a darker colour and a noticeable odour. This is caused by plant material like seaweeds decomposing, and is a harmless process that returns nutrients to the bay.
Dredger vessels, pictured above, and earthmoving equipment are used to transport the sand and sediment around. Although access is still open for the public to the beach, carparks, jetty and river channel, advisory signage should be observed and temporary closures may occur.
The estuary water moving in and out of the river mouth may be turbid (cloudy) while the dredging takes place, as sediment is stirred up. The process takes around 3-4 weeks to complete, depending on weather conditions.
For more information, visit the Parks Victoria information page: