Dredging for recreational access
Transport and Main Roads maintains channels for recreational boating in high-use waterways for access to facilities owned by the department when it is financially and environmentally feasible to do so. With the continuing growth in recreational boating, the expectation for dredging is always high.
Potential new dredging projects are identified through proposals received from councils and port authorities, information provided by boating organisations and individual boat users, plus an extensive ongoing program of hydrographic surveys to monitor changes in channel depths.
Waterways are often a complex network of naturally shallow areas and channels with many of these areas constantly changing due to natural processes. This sometimes results in shoaling that poses difficulties for some boat owners.
Dredging is an excavation activity that artificially deepens or widens harbours and channels to improve navigational safety and to maintain particular design depths. The process of dredging involves using machinery to gather up bottom sediments such as sand, silt or mud. In some locations sediment is clean sand that can be used for land fill or nourishing beaches. In other locations an environmentally responsible method of disposing of dredged material needs to be found for each dredging project.
Due to the natural movement of material, it is not always cost effective or environmentally responsible to dredge in all locations that may be desired by boat owners. Capital cost, potential future maintenance dredging costs and environmental considerations are key factors considered when assessing potential dredging projects.
Dredging intended mainly to benefit commercial vessel operations or within privately leased areas is not usually funded from the Marine Infrastructure Capital and Maintenance Program.
The department focuses its limited dredging funds, drawn largely from recreational boat registration fees, on providing access to all-tide facilities in state boat harbours plus selected high-use channels elsewhere.
The dredging of coastal creeks and rivers is not normally feasible unless the waterway is within a major trading port, where the funding is provided by the port authority from shipping and commercial vessel levies. In such cases the port authority usually carries out the dredging.
Councils and other entities may undertake dredging for any purpose including boating projects that do not meet requirements for funding by the state.
The dredging of channels through bars at the entrances of coastal creeks and rivers to provide access to public boat launching and landing facilities is a low priority for funding allocation. Similarly, channels within coastal creeks and rivers are a low priority. This is because:
- Benefits gained in the short term are usually soon lost through siltation and shifting banks
- The costs of initial capital dredging and ongoing maintenance dredging are prohibitive
- There may be unacceptable environmental impacts on upstream waterway ecology – such as salinity penetrating further inland – meaning that environmental dredging approvals (and supply of suitable environmental offsets) are extremely difficult to arrange.