Australia: EHP Amends Allowable Level of Turbidity in Gladstone Harbour

The Department of Environment and Heritage Protection (EHP) has amended the allowable level of turbidity in two out of six sites in Gladstone Harbour following an application by Gladstone Ports Corporation’s (GPC).

EHP’s Environmental Services Gladstone Regional Manager Don Arnold said the decision to amend turbidity levels, which regulate dredging activity, had been based on additional scientific data that was not available when the original levels were set.

“This decision is based purely on science, which indicates that water quality would remain at acceptable levels with the amended trigger levels.” Mr Arnold said.

“The department’s absolute priority in considering GPC’s application to increase some dredging trigger levels was that there would be no greater impact on seagrass and marine life in Gladstone Harbour.

“The original turbidity management levels were based on limited data available at the time and were, quite properly, very conservative.

“Since these levels were set there has been additional monitoring and additional data for the two sites which has demonstrated that the original trigger levels could be increased without causing harm.

“The new independent data was carefully considered by the Dredging Technical Reference Panel, a committee of technical experts and regulators which was established to oversee all aspects of water quality monitoring in Gladstone Harbour.

“The Panel was satisfied the water quality monitoring program could be amended without impact on the environment, and, through its independent chair, agreed to the amendments.

“The technical experts’ recommendations were also independently considered by State Government water quality and seagrass scientific experts.

“The department has agreed to amend turbidity management levels as requested by Gladstone Ports Corporation for the ‘wet season’ (October to March). However, the approved levels for the ‘dry season’ (March to October) were lower than those requested by GPC.

“This was to make certain that the levels of turbidity would not impact seagrass growth during the main growing season in spring.”

Turbidity levels describe the cloudiness of water which can affect light dependant organisms such as seagrass and reef coral. Although it is generally non toxic to organisms it can affect those which rely on light to sustain life.

Gladstone Ports Corporation has approval to dredge 32 million cubic metres of spoil from Gladstone Harbour and to dispose of it offshore and in a constructed reclamation area.

The amended conditions apply to all dredging activities covered by the Western Basin Dredging and Disposal Project (WBD&DP) and the Wiggins Island Coal Export Terminal (WICET).

Mr Arnold said the Department of Environment and Heritage Protection was taking its responsibilities for the environmental health of Gladstone Harbour and its marine life very seriously.

“Investigations are continuing into fish health issues to assess the condition of fish and potential causes, although testing to date has identified no one single cause for ill fish and no link to the dredging program,” he said.

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Dredging Today Staff, May 3, 2012; Image: westernbasinportdevelopment