Gladstone Ports Corporation (GPC) is not breaching turbidity levels in the Gladstone harbour, nature is.
Western Basin Dredging and Disposal Project (WBDDP) Manager Peter O’Sullivan said all current data reveals the current Spring and King tides primarily drive turbidity levels in the Gladstone harbour.
“Turbidity is a natural phenomenon that occurs in most bodies of water, be it oceans, lakes or rivers,” Mr O’Sullivan said.
“Turbidity is a description of how clear the water is. In simple terms it is a measurement of the water’s muddiness or cloudiness.
“Suspended matter such as clay, silt, and organic matter, as well as plankton and other microscopic organisms can cause turbidity.
“Increased turbidity can also be caused by natural events such as storms, heavy rains, tides and floods, which create fast running water that can carry more particles and larger-sized sediment.”
Mr O’Sullivan said turbidity may also come from sediments eroded from beaches as well as from sediment-laden river plumes and turbidity can also have anthropogenic (man made) origins.
“However, these may vary from wastewater discharges to beam trawling, propeller wash resulting from shipping/boating and of course re-suspension (disturbed soil) caused by dredging,” Mr O’Sullivan said.
“High tides, like what we are experiencing now, bring clay, silt, and organic matter from the Gladstone harbour’s rivers, estuaries and banks where 99 per cent of the time high tides primarily drive turbidity levels in the Gladstone harbour.
“The monthly water turbidity graphs the WBDDP produce each day and are available on our website clearly show turbidity in the harbour rises with every high tide.”
Gladstone Ports Corporation CEO Leo Zussino said water quality monitoring in the Gladstone harbour is conducted independently from GPC and has been part of the GPC’s environmental program since the 1990’s.
“Monitoring of the health of Gladstone harbour commenced following the Curtis Coast Resource Scan in 1994,” Mr Zussino said.
“Since then, over $25 million of water quality monitoring, benthic life testing and seagrass monitoring has been undertaken.
“The project conditioning requires a comprehensive water quality monitoring program involving 16 continuous monitoring sites with 16 additional manual monitors testing water samples to provide actual readings close to the dredges, as well as background readings throughout the Gladstone harbour.”
Mr Zussino said all independent data collected so far shows water quality in the Gladstone harbour continues to be of high standard and similar to pre-dredge conditions.
“The GPC provides the latest water quality monitoring data on turbidity in the Western Basin and Gladstone harbour to the pubic daily on the Gladstone Ports Corporation website and I invite the public to see the data for themselves,” Mr Zussino said.
Dredging Today Staff, June 6, 2012; Image: westernbasinportdevelopment