Wetlands fall prey to salt, says CSIRO

By Chris Spindler The Chowilla flood plain, a wetland of international significance fringing the lower Murray near Berri, is in danger of succumbing to salinity. A five-year study, by the Commonwealth Science and Industry Research Organisation (CSIRO) Division of Water Resources, pointed to rising water tables and accompanying salt as the agent killing river red gums and black box trees along the Murray River. According to CSIRO representative Dr Glen Walker, 120 tonnes of salt a day now enter the Murray River. Addressing the Bookmark Biosphere Trust and South Australian Department of Environmental and nature Resources Environmental Forum at Berri on November 27, Walker said that the rise can be attributed to the installation of Lock 6, regulation of floods by massive storage and irrigation in the area. "To try to overcome the salt problem, a number of salt mitigation schemes have been proposed over recent years. However, the CSIRO studies suggest that none of the schemes put forward so far would be quick or easy. It would take decades, maybe even a century, for ground water pumping to have much effect", said CSIRO team member Ian Jolly. "Unfortunately, enhancing floods is not much a solution either. In the main, benefits in washing salt out of the soil would be offset by increased salinity of the Murray", he said. Studies are beginning to reveal that planting trees to stem rising water tables at Chowilla is ineffective because the ground water is too saline. The environmental forum also discussed changes from the creeping salt in the biodiversity of plants and animals on the Chowilla flood plain.