Victoria’s Channel Deepening Project was dealt a serious blow yesterday when the Blue Wedges Coalition was granted the right to challenge the Federal Environment Minister’s decision to approve the project in a hearing set down for 20 February, three weeks after the dredging was due to begin.

The decision came despite warnings from Port of Melbourne Corporation chief executive Steve Bradford that it would cost the port around $250,000 for every day of delay and some injudicious comments from Premier John Brumby, who claimed that Melbourne would become a “backwater” like Adelaide if the channel deepening didn’t proceed.

But as dredging has approached, the project has been subject to ever greater scrutiny, and ever greater criticism. Here, Crikey offers an incomplete list of the possible environmental damage that underpins the growing opposition to the project.

Dredging the Lower Yarra

  • The Lower Yarra estuary is where the tide meets the streamflow and sediment and pollutants accumulate. Grab dredges will be used to remove this sediment which will stir up as much sediment as they load onto barges. The tidal flow will take this plume past the CBD on the high tide twice daily and as far as Collingwood. This will spread to toxins upstream, reduce the oxygen in the lower river and may, on occasions, create odours from the hydrocarbons in sediment in particular.
  • Southbank from the Exhibition centre to the city may have to be shut down due to sludge fumes released from toxic sludge flowing through the CBD on high tide.
  • The toxic sediment flows have the potential to affect events like Moomba, rowing clubs, water tourist ferries and other recreational activities on and around the Yarra River.
  • The loss of Commonwealth listed endangered fish species such as greyling that have to travel through the estuary each summer to breed.
  • The potential loss and contamination of the migratory birds that used the Yarra mouth to loss of migratory birds due to contamination of Yarra and Koroit Creek mudflats they feed on.

Transport and dumping of toxic sludge back into spoil grounds

The barges that will take the toxic waste to the spoil grounds along the east coast of the bay are likely to spill toxic sediment in transit. This risks:

  • Hundreds of thousands of beach visitor spending days lost with even the occasional closure of east coast beaches;
  • Loss of east coast commercial and recreational fisheries after dredging and to possible contamination of fish and shell fish;
  • Compromising or loss of yachting opportunities due to the impact of exclusion zones a water quality.

Opening of heads

The maximum predictable high tide outside Port Phillip heads is one metre greater than inside before dredging. There is disagreement regarding the maximum increases that the opening of the heads will cause and the impact of the storm surge heights that could be reached inside the Bay. This risk and uncertainty is amplified by the ongoing erosion of the heads set off by the trial dredging that may be amplified by further works. Risks include:

  • Groundings of commercial shipping using the heads due to changes in tidal flow and the narrowness of the shipping channel relative to the size of the ships using it. Such an accident could create a catastrophic oil spill;
  • The loss of thriving commercial dive, fishing charter and dolphin watching businesses;
  • Flooding of southbank, the casino and ‘Yarra-side’ businesses;
  • Tidal inundation of marinas and yacht clubs;
  • Tidal inundation of Werribee sewerage farm;
  • Loss of Mud Island nature reserve due to erosion from changed tidal flows;
  • The loss or compromise of blue mussel aquaculture at Port Arlington.