Channel Deepening

Article by Peter Fear, The Scuba Doctor — July 2005

Note: Clicking on the pictures through this article will popup larger versions of the pictures.

PPlume of sediment from trial dredgingDid you know it has the potential to destroy Port Phillip Bay's unique underwater environment and decimate the dive industry?

The two main areas of concern are the removal of millions of tons of sand from the South Shipping Channel, beginning just inside Port Phillip Heads, to the other end of the channel off McCrae and the destruction of pristine reef from dive sites known as The Plateau and Rip Bank in the entrance.

The reason for this project is so that larger container ships with deeper draughts carrying more containers can enter the bay and some container ships already visiting, can do so fully loaded.

Plume of sediment close to a pierDid you know the entrance to Port Phillip is narrow with a bay of huge volume, filling and emptying like a bottle, creating strong flows at the neck. It is this, along with the underwater topography that gives us our unique marine environment. An environment so special that the State government recently created several Marine reserves in the area to protect this enviroment which they so proudly boasted and promoted. Remember the television add campaign telling us what great fella's they are protecting this area.

The removal of reef in the entrance has the potential to dramatically affect the level of water in the bay and the duration and timing of slack water. Consultants commissioned by the Channel Authority claim their studies indicate the level of water in the bay will only increase by a maximum of 1 cm, but nobody can predict the effects of nature.

Did You Know That...

  • The sediment spreads much further out to sea than most thinkThe areas of Rip Bank blasted in the 1980's to deepen the channel have still not recovered.
  • The Plateau is almost surrounded by dropoff's to 90mts plus, and any method of removal of reef from the top could cause a cascading effect of rubble down the walls, further destroying this unique habitat.
  • The boundary of the Lonsdale Wall marine reserve is only a matter of a few meters from the areas of The Plateau and Rip Bank that they intend to destroy and consists of the same unique environment.
  • The sediment speads over a huge areaSediment created by dredging does not travel out to sea before deciding to settle. It is distributed up to many kilometers out to sea and over the marine reserves, scallop and sea grass beds in the bay by the six hourly tidal changes.
  • Melbourne as a container port will be at its maximum capacity by the year 2030 with the channel deepening.
  • Plume of sediment near Popes EyeThe spoil grounds for this dredging were just north of Popes Eye and an area of the scallop beds off Rye, although they claim there were no scallops there at the time. Who are divers to argue! This area is dived almost daily by someone, for a feed.
  • Whatever or however they decide to use or dispose of the spoil, the cost is insignificant in the overall billions of dollars involved with this project.

Historic sites may be destroyed

  • The war grave and historic wreck of the Goorangai is in the middle of the south channel and rises above the depth required for these deep draught vessels.
  • The wrecks of the 'Eliza Ramsden' and the 'Hurricane' lie next to the south channel and could be covered or partially covered by sand.
  • The view of the Maritime Heritage Unit is that it is of no consequence if these wrecks were buried under sand as it would preserve them longer!

We stopped Scallop Dredging but permit Channel Dredging

  • The effects of continuous scallop dredging up to the early nineties decimated the sea grass and scallop beds and had a disastrous effect on fish stocks.
  • The public couldn't see the results, so were ignorant.
  • The scallop dredging was finally stopped after a concerted campaign and a then State Government Minister, Mr. Steve Crabb, was taken diving to see the devastation for himself.
  • When scallop dredging was stopped the scallops and sea grass began rejuvenating, and all forms of life returned making the bay the healthiest today that it has been for many years.

And there will be more Maintenance Dredging

  • Maintenance dredging was last carried out in the south channel December 2002 when vizability dropped from 25mts plus to zero in a day. It took weeks to recover after the completion of dredging.
  • Maintenance dredging to maintain the required depth and width of the south channel after deepening will be more frequent and extensive, zero visability and further destruction. The last two maintenance dredging operations were six years apart, despite Mr Bracks claim it happens all the time.

They've Already Decided!

  • Plume of sediment spreading through the headsThe trend in shipping is to build larger ships with shallower draughts. These container ships already exist but we are told they only work the east-west world container route not the north-south route, of which we are a part.
  • By the time this goes to print the government will have most likely, already announced funding for the project.
  • The final decision will be made or controlled by a panel of government elected bureaucrats.
  • Approval for the construction of new container wharf's to accommodate the increased volume of shipping has already been given and work commenced.
  • The project has the backing of the Victorian Chamber of Commerce and Industry, the unions and obviously the shipping companies, to name but a few.

Likely effects...

  • The deepening will take many months to complete and make it dangerous and impossible for recreational industries to operate.
  • Divers won't be able to dive, snorkellors won't be able to snorkel our marine reserves with the dolphins and seals, the recreational fishing charter industry will cease and recreational fisherman will have a long lean spell. Professional cray and other fisherman will also suffer. The long term affects of this project on these industries and the health of Port Phillip could be catastrophic.
  • Consultants have been engaged to determine the affects on these industries and their right to compensation.
  • The flow on affect of a non functional Victorian dive industry will lead to reduced certifications, loss of sales, non existent dive charters, loss of industry jobs, closure of shops and undoubtedly bankruptcy for some.

What's Being Done?

And this was only the 'trial' dredging!Who cares? And who's doing anything? You tell me, apart from concerned individual divers and a small number of dive shop owners, an environmental group called Blue Wedges. No one else seems to give a damn.

Maybe it's time the dive industry, training agencies and wholesalers that thrive in the industry, pool their collective might and help save the Victorian industry and environment, but then, it's not a tropical reef is it?


Several alternatives have been suggested but it seems they have all been studied and the costs are prohibitive, although access to that information is questionable. One point of view is that a deep water port already exists in Westernport. If a container terminal was constructed to accommodate larger vessels, which eventually has to happen anyway, there may be no need to destroy our marine inheritance...


Information on the project can be accessed on

The Blue Wedges Coalition web site can be found at

Suunto D5 at The Scuba Doctor Dive Shop