WetlandCare Australia -Projects Archive
Restoration Strategy for Belongil-Cumbebin Wetland
The Wetland Restoration Strategy (WRS) for the Belongil-Cumbebin Wetland Complex (B-CWC) is part of the North Coast Catchment Management Authority strategy to provide better management of the natural resources. The WRS builds on previous work conducted by a number of organisations and stakeholder groups working on issues such as acid sulfate soils, estuary management, stormwater management and weed control.
During the course of the project Wetland Care Australia seeks to work with the community to produce a clearly stated vision for the future of the Belongil-Cumbebin Wetland.
This vision must be based on a balance of the best science available, respect for the rights of individual landholders, the needs of the wetlands and the Belongil estuary, and what is practically achievable in restoration.
The primary objectives for the WRS of the Belongil-Cumbebin Wetland Complex are to produce:
- An Environmental Management Plan for the Belongil-Cumbebin wetland complex addressing all Natural Resource Management issues relevant to the area.
- A priority list of NRM issues and sites for strategic on-ground works.
- A strategy for the brokerage of funding to implement the WRS recommendations, including the provision of technical/professional assistance to landowners where necessary.
- Stakeholder ownership and acceptance of the WRS to achieve comprehensive adoption of recommendations as well as implementation.
The implications of any further encroachment of development into the Belongil-Cumbebin Wetland Complex also requires consideration.
Land Uses - Grazing
In the past landholders cleared their holdings, including the wetlands, to provide grass for livestock. Clear felling of Melaleuca was carried out in the 1950s-70s to provide fuel for the boilers at the Byron Bay abattoirs, piggery, butter factory and whaling station, as well as providing the cordwood which the Council used as a stabiliser to construct roads across the wetlands.
Much of the present Melaleuca is predominantly spindly and is not representative of the original old growth vegetation, which is still evident in several remnants (Draper, 2002).
Constructed drain and acid water
NSW Government incentives encouraged drainage of wetlands to promote agricultural production. By 1913, over 6 kilometres of major drains had been constructed west of the Belongil estuary. Individual landholders have subsequently constructed connecting drains.
The Belongil Drainage Board now administers 8 km of agricultural drains and there is another 40 km of secondary drains constructed within the catchment, including Council and private works. The area of impact of the drains extends beyond the wetland area and includes grazing, industrial and urban land.
What's wrong with draining wetlands?
Excessive drainage of coastal wetlands can cause sudden and large increases in acidity transported to the estuaries. It is now recognised that water quality problems associated with acid sulfate soils is largely due to the drainage of marginal agricultural land. Such drainage works have significant detrimental impacts on the health of waterways, including a reduction in the number and area of freshwater wetlands, reduction in habitat for fish and other estuarine species, fish diseases and death due to acid discharge, and alienation of agricultural land due to acid scalding (Tulau, 1999). Other impacts of draining wetlands include the loss of flood buffering, interruption of the food chain of the estuary, degradation of wildlife habitat, and altered nutrient cycling functions.
The West Byron Sewage Treatment Plant (WBSTP) occupies 105ha near the edge of the Belongil-Cumbebin Wetland Complex. A majority of the tertiary treated effluent from the site, after passage through a large constructed wetland system, is currently reused on a 24ha Melaleuca restoration site.
Any unused treated effluent from the constructed wetlands is released into the drainage network, ultimately entering Belongil estuary via the Union Drain. Council's new strategy embraces demand management, centralisation of sewage treatment and management at West Byron, the maximum practical percentage of effluent reuse, and the use of large constructed wetlands as an integral component of the effluent management system.
Actions to reduce acid flows from the drainage network include:
- placement of in-drain water control structures at strategic points, which would keep the water table relatively high and/or
- redesign of drains through shallowing and widening
Options for management of constructed drains in the Belongil catchment have been examined at several workshops, meetings, and most recently at the 2002 Belongil Wetland Think-Tank Symposium (Tulau, 2001). These options include interim drain management using in-drain devices such as dropboards or gates, and drain network re-design.
Several flora and fauna studies have been completed for the Belongil area in recent years, including Parker (1996), Landmark et al. (1999), WBM (2000) and Davis (2001).
The main wetland vegetation associations of the Belongil catchment include:
- Mangrove Forest and Woodland
- Swamp Sclerophyll Forest and Woodland
Five plant species that occur within the Belongil-Cumbebin catchment are listed as threatened under the Threatened Species Conservation (TSC) Act. These are the Red Lilly-Pilly (Syzygium hodgkinsoniae), Durroby (Syzygium moorei), Stinking Cryptocarya (Cryptocarya foetida), Swamp Orchid (Phaius tankervilleae) and the Arrowhead Vine (Tinospora tinosporoides).
Since drainage, the area of wetlands has been reduced by about two-thirds due to clearing for agriculture. There has been a loss of connectivity, altered hydrology, as well as barriers (e.g. constructed drains and roads) to the movements of non-flying terrestrial animals. Much of the area has been invaded by weeds, reducing the ability of the wetlands to perform their ecological functions. Overall condition of paperbark trees in the catchment is poor, and this is attributed to the stresses placed on them by human activities. Fragmentation of the wetland ecosystem explains why the vegetation in the study area compares so unfavorably with the 'ideal'.
Overall wetland health is poor in the Belongil system, due mainly to human disturbance through clearing, drainage and encroachment of other land uses. The remaining wetland areas are mainly in relatively small units that are isolated from others by roads, railway lines, drains, and inhospitable agricultural land. The main threats to a sustainable ecosystem fall into the three categories of disturbed hydrology, competing land uses and biological invasion
Coastal wetlands generally provide habitat for birds, frogs, invertebrates and fish species, as well as having a close ecological connection with estuaries. Most are dependent on good water quality traditionally associated with healthy wetlands.
Two-thirds of the fish stocks harvested in NSW coastal waters spend part of their life cycle in wetlands and estuaries.
Thirty two (32) vulnerable fauna species listed under the Threatened Species Conservation Act (1995) have been recorded within the Belongil-Cumbebin basin. Three of these are threatened, including Little Tern, Beach Thick-Knee and the Mitchell's Rainforest Snail.
Despite the high level of disturbance, the Belongil-Cumbebin wetland system is most remarkable for its avifauna. Over 195 species have been recorded in the area. This rich bird life is seen as resulting from the very high biological productivity of the remnant Belongil-Cumbebin area.
Estuary Opening to the Ocean
The Belongil Estuary is artificially opened using an excavator 3-5 times per year to supplement natural openings. This is done to reduce the risk of flood damage to the Byron Bay Town Centre and other land in and adjacent to the Belongil-Cumbebin Wetland Complex.
The opening process involves an excavator being used to dig a channel to allow the build up of water to rush out. This creates a channel allowing tidal water exchange for several weeks to several months, before sand builds up again and blocks the entrance.
Other reasons for estuary opening is to:
- Minimise fish kills in the closed estuary;
- Enhance and protect ecological communities in the catchment and estuary that have developed in response to the historical opening regime; and
- Assist in managing polluting processes, particularly acid sulfate drainage waters, until more refined remediation strategies are further implemented.
Estuary opening encourages the release of fish to the ocean as well as yabby and fish recruitment into the estuary. It also allows saline intrusion along the estuary and drainage network.
The main disadvantage of tidal intrusion is the potential medium to long-term ecological impacts on the upper estuary environment. The main advantage is in the avoidance of short-term catastrophic pollution events associated with natural and artificial openings, by buffering and reducing concentrations of pollutants such as the products of acid sulfate ground water.
Where to From Here?
Over the next 6 months, the project partners will:
- Hold a Community Think-Tank to further develop the Belongil-Cumbebin Wetland Complex
- Continue to liaise with landholders and attempt to address their concerns
- Seek ongoing guidance from the Belongil Community Working Groups
- Monitor progress and report to the community
- Display the Draft WRS
- Incorporate public comments
- Make recommendations to NRCMB and BSC
- Develop funding strategies
Throughout the development of the WRS, special emphasis has been placed on the community consultation process, to ensure the highest level of ownership. The resulting strategy will pave the way for the implementation of a comprehensive WRS.
For more information contact:
Bob Smith, Regional Wetland Specialist
WetlandCare Australia on 02 6628 3472
Update on significant developments in the Belongil Wetland Restoration Project following our 'Think-Tank' held on 22 July.
There is a high level of interest in modelling sea level rise as the basis for amendments to the Local Environmental Plan with the view to getting people and non-compatible land uses out of the existing wetland areas and allowing sea level rise to occur without adverse impacts on private property and the associated public cost of engineering protection.
Wetland Care Australia has recently collected detailed vegetation quadrat plant community descriptions and photography compatible with the elevation data, allowing predictive modelling of wetland vegetation change likely to occur as a result of sea level (hydrological) change.
Wetland Care Australia has a 70 slide PowerPoint presentation and a collection of about 80 recently flown oblique aerial photos taken specifically for the Think Tank presentation.
From Wetland Care Australia's point of view, aiming get interested parties on the path to strategic planning for sea level rise by allowing natural wetland rehabilitation, will achieve an enormous amount.
For more information contact Bob Smith, Regional Wetland Specialist, Wetland Care Australia