Wetland Management
A Management Plan for Gumma Gumma Wetland
In early 2004, Nambucca Shire Council commissioned WetlandCare Australia to undertake a preliminary assessment of management issues and options for the Gumma Gumma wetland, near Macksville NSW.
Project Aim
Through the Gumma Gumma project, Nambucca Shire Council sought to reinstate:
- Productive values of the backswamp for both grazing and wetland values;
- Natural water level characteristics;
- Fish passage and estuarine habitat linkage to the Nambucca estuary; and
- Improved water quality discharge from the backswamp.
Issues
The main issues affecting the wetland centre on the historic lowering of the water table. The reduced water levels are attributed to floodgates and drains that date back to the mid 20th century. This has altered the natural values as well as reducing the potential for grazing on the wetland area. Over-drainage of soils teamed with dry seasons has contributed to acid/iron discharges and the formation of seasonal scalds associated with acid sulfate soils and saline tidal water inundation.
Community Consultation
A range of options that could be addressed through practical works were discussed at several onsite meetings with key stakeholders. The preferred option was to install temporary drop board weirs for evaluation on a trial basis.
The Plan Arising from the Community Meeting
There was consensus at the final meeting that removal of the old floodgated culvert should occur provided that a new water control structure was installed further up Gumma Creek.
Operation of the dropboards is to be co-ordinated by a landholder representative in consultation with other stakeholders and WCA to achieve:
- Prevention of king tide salt intrusion along the constructed drain especially during prolonged dry periods;
- Seasonal retention of freshwater within wetland especially during the onset of dry season (mimicking natural system);
- Tidal overtopping of the structure (removal of some boards) at all other times to allow fish passage with the exception of when salt intrusion threatens upstream freshwater vegetation species; and
- Drop boards may be removed during wet seasons to facilitate fish passage and drainage to natural ground level.
Monitoring
A monitoring program is underway that addresses the area of tidal and freshwater inundation (using tidal gauges), vegetation changes/correlation with water levels (photo monitoring), and proposed water quality above and below the dropboard culverts, as well a record of water level manipulation/rationale via adjustment of the dropboards.
Trial Review and Reporting
All water level, vegetation photo and water quality monitoring will be reviewed after 12 months and a report furnished by WCA to all stakeholders and the stakeholder advisory committee to seek a consensus for the future direction of the trial and as the basis for an extension of the trial for another 2 years.
Implementing the Plan
The proposed works may have far reaching effects and as such require licenses and approvals from a range of Government Departments. A management team has been established consisting of landholders, State and Local Government representatives and a wetland expert.
The response of natural systems is not always easy to anticipate, and in this case monitoring of the trial installation is proposed. It is hoped that if the initial trial is successful, a more comprehensive strategy for the restoration of Gumma Gumma wetland will be developed.
Or Contact
Brigita Arrowsmith
Project Officer
WetlandCare Australia
PO Box 114
Ballina NSW 2478
P: 02 6681 6069
M: 0439 022 402
E: brigitaarrowsmith@wetlandcare.com.au
Bob Smith
Wetland Management Consultant
WetlandCare Australia
1 Brown Ave
Alstonville NSW 2477
P: 02 6628 3472
M: 0407 456 367
E : bobsmith@wetlandcare.com.au
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