Mooloolaba boat harbour dredging

The Mooloolaba harbour and entrance training walls were built in the late 1960's. Since that time, sand shoaling events have occurred regularly in the entrance channel.

Maintaining a safe navigable entrance here is crucial for all boaties. We aim to keep the entrance clear to a design depth of at least -2.5m Lowest Astronomical Tide (LAT) at all times.

Direction of sand transport around Point Cartwright

Channel shoaling

During a shoaling event, sand accretes to form a shoal (like a sand bar). The shoal decreases the water depths making navigation more hazardous.

To improve safety, dredging removes the sand shoal by pumping the sand onto Mooloolaba Beach. The dredge stays in position and continues to remove sand until safe depths are reached. The 2020–2021 shoaling event required almost continuous dredging from September 2020 to November 2021.

Aerial image of the dredge in the Mooloolaba channel

Current dredging strategy

We have contracted a local Sunshine Coast contractor, Hall Contracting, to dredge the channel entrance.

This arrangement allows a dredge to be available on short notice, with cost effective establishment and standby rates. A small cutter suction dredge is used, as this plant is manoeuvrable and small enough for boaties to pass safely whilst in use and maximises time on task through a shallow vessel draught.  

Other types and sizes of dredges were investigated. These dredges are generally not considered viable for this location as they are subject to similar swell and wind limitations as the smaller dredge. The size and draft of the larger dredges would need deeper water to operate (~3m). This is often not possible during a shoaling event as the dredges are limited by the tide and would be less efficient due to their inability to operate for much of the daily tidal cycle. 

A permanent pipeline was installed in 2013 along the eastern breakwater wall and then runs across the channel anchored on the riverbed. This makes dredging more efficient with less impact on boaties accessing the harbour. The dredged sand is pumped onto Mooloolaba Beach by the pipeline that runs under the beach.

Active dredging in the channel with pipeline connected at Mooloolaba

Current dredging work

Hall Contracting's dredge was remobilised at the entrance just before the major South East Queensland flood event in late February 2022, and it had been dredging in the entrance channel sporadically, when weather conditions allow.

Recent good weather has allowed dredging to resume full-time from 30 May 2022 and the shoal has now been cleared. The latest hydrographic survey undertaken on 2 June 2022 has shown the channel cleared to -2.5m LAT. The dredge will continue working to deepen the entrance to -3.5 m LAT to allow for any further infill of material. 

Hydrographic surveys continue to be carried out regularly to monitor depths in the entrance channel.

Boaties are reminded that coastal bars are constantly changing. Plan your crossing of the Mooloolah River entrance bar and navigate with caution. 

The Mooloolah River entrance is designated as a coastal bar. This means that each person on board an open boat less than 4.8m in length must wear an appropriate lifejacket while crossing the coastal bar.

Stay up-to-date with the latest Notice to Mariners advice to see if your crossing will be impacted.

Pipeline pumping sand from the channel and depositing on the beach

Entrance monitoring cameras

In July 2021, we installed cameras to monitor the wave conditions and dredging activity at the channel entrance. The cameras are fixed to the 2 towers at the end of each Mooloolaba breakwater, looking down into the channel. A photo is taken every 15 minutes.

Investigations into a long-term solution

In 2014 an investigation into options to manage shoaling in the entrance was undertaken by WBM Oceanics (now BMT). A 60m extension to the eastern breakwater, to intercept most of the sand before it enters the channel, was determined as the preferred option. 

Proposed extension to the channel eastern breakwater

In February 2019, coastal engineering consultants Kellogg Brown & Root Pty Ltd started the detailed design work of the 60m breakwater extension. The design was tested at the Queensland Government Hydraulic Laboratory through physical modelling using a 1 in 41 scale model. The design was modified and included analysis of concrete armour units for the construction of the breakwater.

Stakeholder and Community consultation will occur in the second half of 2022. Consultation will run alongside of the environmental approval process.

Download the shoal management options report for the Mooloolah River Entrance

Download the design report for the Mooloolaba Boat Harbour Eastern Breakwater Extension 

Download the constructability report for the Mooloolaba Boat Harbour Eastern Breakwater Extension

Physical model testing of the proposed lengthened breakwater

Contact us

If you would like to register your interest in this project and be added to the stakeholder email contacts for further updates, please email the project team:

Last updated
23 January 2023