Dam?s chemical cocktail
By RACHEL SCOLLAY
SOIL contaminated with toxic DDT and arsenic lies submerged beneath the Emigrant Creek Dam, which Rous Water is planning to reinstate as the main water supply for Ballina and Lennox Head. The dam, pictured right, was built over an old cattle dip where both chemicals were used ? arsenic in the 1940s and DDT in the early 1960s. Although Rous Water has confirmed the presence of both chemicals in the sediment, periodic testing of the water has shown no traces of either chemical. Arsenic is a known carcinogen and DDT, which has been also linked with cancer, bio-accumulates in the body over time and can cause severe hormonal disruption. The dam was built in 1968 and was Ballina's main water supply until Rous Water took it over from the Ballina Shire Council in 1988. Since then, Rocky Creek Dam near Dunoon has been the shire's principal water source, although Emigrant Creek Dam is still used. In 2002, in preparation for Rous' new $9.5-million water treatment plant at Emigrant Creek Dam, Rous Water drew down the dam's water level and environmental consultants carried out sediment tests. Rous operational services manager Wayne Franklin said the results revealed arsenic and DDT contamination. However, he said that since the 1990s, Rous Water had done 'periodic' tests on the water and found no chemical contamination. Speaking from Adelaide and without access to files, Mr Franklin was unable to elaborate on the testing regime used to give the dam water a clean bill of health. However, toxic chemical expert Jo Immig, who works with the National Toxics Network, said many factors could influence test results ? including the precision of equipment and when they were taken. She said she was not familiar with the dip site, so could not comment specifically, but the fact that contaminants were in the sediment and not in the water did not necessarily mean 'a big tick'. "If we had a lot of rain, or the sediment was stirred up, then it could still get in the water column," she said. "You wouldn't want contaminated sediment anywhere. But it is particularly concerning if the water sitting on top of it was potentially going to be used as drinking water." Ms Immig said DDT was 'a real nasty' because it persisted for long periods in the environment. She said one of the more concerning things about DDT was the hormonal disruption it could cause. "It's a new area that hasn't really been studied before, but they're finding that extremely low levels in the environment can have profound negative impacts on the hormonal system," she said. She said DDT was stored in fatty tissue. One of the only ways the body could get rid of it was through breast milk. Arsenic on the other hand was a known carcinogen. "Depending on the type of arsenic, it can be quite residual," she said. Mr Franklin said even though Rous Water was 'comfortable' with the water quality at Emigrant Creek Dam, two years ago it installed $400,000 carbon filters at the current water treatment plant. These would remove any toxins from algae and absorb any chemicals. Rous Water would be also carrying out further investigations in conjunction with the Department of Primary Industries (DPI), he said. Meanwhile, Mr Franklin said the new Emigrant Creek Dam water treatment plant would proceed as planned.