ADDITIONAL findings on how water flows from the Big Swamp and affects surrounding areas will be presented by the Water Research Laboratory (WRL) at the University of NSW in an upcoming draft report to Greater Taree City Council.
The city council asked Dr Will Glamore and his team of researchers with the WRL, who are performing the hydrological study for Big Swamp, to provide additional information on what kind of increased water levels if any at all could possibly be experienced at Harrington as a result of the Big Swamp project improvements.
Concerned residents and landowners, including members of the Harrington Community Action Group, met last week at the Harrington Bowling Club to discuss the issue with Dr Glamore.
Dr Glamore outlined how water from the Big Swamp area actually flows into Pipeclay Canal, then into Cattai Creek and into the Manning River.
Despite the similar names, Dr Glamore underscored that the Big Swamp between Moorland and the Cattai Wetlands should not be confused with the Great Swamp, which is within the nearby Crowdy Bay National Park, next to Harrington.
Wards Creek near Harrington is fed water from the Great Swamp, a separate system to that of Big Swamp, according to Dr Glamore.
"Water from within Big Swamp does not flow directly into Harrington and improving water quality will not impact downstream flooding," Dr Glamore said.
"The water from the Big Swamp area flows into Pipeclay Canal, then into Cattai Creek and into the Manning River."
Additionally Dr Glamore determined that the water from the Big Swamp catchment represented only about one per cent of the total water volume entering the Manning River during flood events.
"The Pipeclay Canal catchment is very small compared to the large Manning River catchment and the majority of water comes from rainfall events upstream of Wingham."
Also discussed at the meeting was the future rehabilitation of acid sulphate soils within the Big Swamp area.
Dr Glamore highlighted that "deep flooding of farmland within Big Swamp is not our preferred solution to the problem", outlining instead a process of making some drains shallower, rewetting the soil and limiting over-drainage.
The shallow drains would then lessen acid drainage and acid could be further buffered by the strategic removal of floodgates from drains along the side of Pipeclay Canal.
Floodgate removal would allow tidal waters to reach further into the Big Swamp area, lessening the impacts of acid sulphate soils causing acid plumes in the Manning River, which result in fish kills and a reduction in productivity for oyster growers.
Dr Glamore told the meeting that the Big Swamp area has some of the worst acid soils he has seen in NSW and as a result of the recent rainfall events, is expecting to see an acid plume in the Manning River in the next week or so.
In anticipation of this event Dr Glamore has had a number of highly trained university staff undertaking water and soil sampling in the last two weeks and will continue to monitor the situation as the Big Swamp area slowly drains into the Manning River.
The project partnership has been of great value to council, not only providing council with critical information for the future improvement of water quality within Big Swamp but as the latest rainfall event has occurred towards the end of the study work, this has enabled WRL to undertake extensive fieldwork in examining an actual acid discharge from the catchment.
A spokesman said Greater Taree City Council is pleased to have been able to partner with the UNSW on this work, and anticipates that Dr Glamore's work will help council and the community better understand the problem of acid sulphate soils. The upcoming draft report will give further information on what work can be undertaken to improve the situation.
"Council is committed to continual improvement in the environment and water quality in the Manning River, all of which has a lasting and positive economic effect for the Manning Valley," the spokesman said.