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Recreational and commercial fishermen point to the recent decision to reduce environmental flow from the Yarra to supplement Melbourne’s water supply as a likely contributor to the current outbreak of lesions in several popular fish species. Drought conditions combined with deliberate reduction in environmental flows from the Yarra means higher pollutant and nutrient concentrations have entered the Bay, and then the food chain.  

 “EPA’s warning not to touch or eat fish found in the north of the Bay following multiple findings of fish - flathead, whiting, trevally and others with obvious lesions is a loud and clear warning call. Mr. Garrett and Mr. Brumby must call a halt to dredging and commission a full and independent study into what might happen to the Bay if dredging, drought and deliberate reduction of environmental flow continues”.

The big question is: What might be the outcome if a sustained dredging campaign in the Yarra, (removing 5 kms and 10 million cubic metres of riverbed) releasing the one hundred years of toxins currently trapped and relatively inert deep in the Yarra sediments is added onto the effects from drought and reduced environmental flow?

The Port of Melbourne Corporation has not considered cumulative impacts of drought, deliberately reduced environmental flow, release of toxins and sustained turbidity from dredging the Yarra. Eight months of dredging the Yarra will impose additional stresses on its ecosystems by orders of magnitude to what those ecosystems are already experiencing. Something is already wrong, obviously, and dredging is another stress on top, with unknown consequences, perhaps by orders of magnitude”, says Jenny.

What’s more, the human health risk assessment commissioned by the PoMC relied on water samples taken from a minor maintenance dredging campaign, (using a smaller and different type of dredge to what PoMC plans to use in the Yarra) and which went nowhere near the Yarra, where the highest concentrations of toxins are. Even so, their inadequate assessment reveals that 100 people may become ill and 10 may develop a serious illness –which the PoMC rates as a “minor” and acceptable risk. “No-one I know thinks it is acceptable for 10 people to acquire a life threatening illness just so channel deepening can happen. Who would - other than the PoMC?” says Jenny.

Fishermen have commented that fish lesions are seen from time to time, but nothing like this has been seen since the last major drought which also coincided with when scallop dredging was banned in the Bay in the mid 1990's.