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Wetlands

Gwydir

Introduction

Water from the Gwydir River, in the north-west of NSW, supports a major irrigation industry and provides income and employment for thousands of people. As well as producing food for local consumption, it is also a source of agricultural exports for Australia. Water from the Gwydir also supports natural processes and significant wetland systems. The Gwydir wetlands, located at the bottom end of the Valley, not only support bird populations that are listed under the China/Australia (CAMBA) and Japan/Australia (JAMBA) agreements on migratory birds they are also recognised as internationally important under the Ramsar Convention.

Wetlands of the Gwydir Valley

Wetlands of International Importance

The following information on Ramsar Wetlands has been adapted from the Ramsar Pages of Environment Australia's Website. More information on these wetlands and the reasons for their inclusion as Ramsar wetlands are available on either Environment Australia's Website or The Ramsar Bureau Website.

Gwydir Wetlands: Gingham and Lower Gwydir (Big Leather) Watercourses (Wetland B on Map 2)

The Gwydir wetland was accepted as a Ramsar site on the 14/06/99. It is one of the largest inland wetlands in New South Wales with a designated surface area of 823 ha. The wetland is home to half a million nesting and breeding waterbirds. The designated area is entirely privately-owned and forms part of a much larger wetland system in the Murray-Darling drainage system. Large parts of the surrounding land are used for cotton growing and cattle grazing, with the latter use continuing under careful regulation, as part of the wise use of the site. A Memorandum of Understanding on the designation and future management of the site was signed on World Wetlands Day 1999 by the four landowning families and officials of the State and Commonwealth governments, the World Wide Fund for Nature, and the National Parks Association.

Gwydir
Source: Tracy Fulford (DLWC)

As mentioned above, the Gingham and Lower Gwydir (Big Leather) Watercourses are part of a much larger wetland system called the Lower Gwydir Wetlands. More information on the larger Lower Gwydir Wetlands is provided in "Feature on the Lower Gwydir Wetlands".

Wetlands of National Importance

The following wetland summary has been adapted from the Directory of Important Wetlands in Australia, 3rd Edition. More information on these wetlands and the reasons for their inclusion in the Directory of Important Wetlands in Australia can be found on Environment Australia's Website.

New England Wetlands (Wetland No. 23 on Map 2)

The New England Wetlands fall partially within the Gwydir Valley in the Barwon Region and partially within the North Coast Region. A full description of these wetlands is provided on the "North Coast Region Wetlands and Activities" pages of this site.

Feature on the Lower Gwydir Wetlands

Introduction

The Lower Gwydir wetlands are among the most extensive and significant semi-permanent terminal wetlands in north-west New South Wales (Keyte, 1994). The Lower Gwydir wetlands actually comprise two distinct wetland areas, the Gingham Wetlands to the north and the Lower Gwydir Wetlands (originally referred to as the Big Leather wetlands), to the south. In total the wetlands cover an area of 102, 120 ha (ANCA, 1996).

Gwydir
Water spilling out of the Gingham channel
Source: Neal Foster (DLWC)

Vegetation

The two sections of the Gwydir wetlands are biologically similar. Both are dominated by Water Couch, Rushes, Sedges and various other aquatic plants. Coolabah, Lignum and River Cooba dominate the woodland areas of the wetlands. When in flood, the Gwydir wetlands transform into a vast meadow of aquatic plants. Dominant species include Cumbungi, Marsh Club Rush, Water Couch, Watermilfoil and various Spikerushes (Fulford, In Prep).

Gwydir
The Gingham Waterhole
Source: Neal Foster (DLWC)

Waterbirds

Over 235 different species of birds have been recorded in the Lower Gwydir wetlands. Of these, 134 have been observed to use the wetlands for breeding. At least five endangered species and nine species of migratory birds that are listed under CAMBA and/or JAMBA have been recorded in the wetlands (Fulford, In Prep).

birds
Breeding colony of Straw-necked and Sacred Ibis
Source: Neal Foster (DLWC)

Frogs

The Gwydir Valley wetlands are characterised by a diverse and abundant frog population. In particular the cracking clay soils of the wetlands provide an excellent habitat for many frog species. 

Approximately 14 different species have been recorded in the wetlands. The most common of which are the Barking Marsh Frog, Spotted Marsh Frog, Salmon Striped Frog, Green Tree Frog, Broad Palmed Frog and the Crucifix Frog.

Frogs are also an important food source for water birds. 

Nomination under Ramsar

In 1999, four landholders in the Gwydir Wetlands created history, being the first in Australia to voluntarily list portions of their properties under the Ramsar Convention on Wetlands. More than 800 hectares of the Lower Gwydir wetland area is now listed under the Convention.

Royal Spoonbills
Royal Spoonbills
Source: Neal Foster (DLWC)

Grazing in the wetland meets the Ramsar Convention criteria on wetland's sustainable use. Water sharing rules, which are an essential element of the planning and resource management framework, have also been in place for the wetlands since September 1995 (Fulford, In Prep).

Environmental Flow Rules

Their relevance to the Wetlands of the Gwydir Valley

The Gwydir River and associated wetlands and floodplains have changed significantly from their natural state as a result of dam building and the use of water for agriculture, recreation, industry and domestic needs. While this use of water generates significant economic benefits, including over $200 million of irrigated agricultural products in the Gwydir, there is clear evidence of increasing environmental stress within the river and, in particular, in important wetland areas.

An Environmental Flows Committee was set up in the Gwydir in 1995 to recommend environmental flow rules. These were introduced for the first time in the Gwydir in the 1995/96 water year.

In late 1997, a River Management Committee (RMC) was established for the Gwydir to build and expand upon the work done by the Gwydir Environmental Flows Committee. Click here to view a PDF of the River Management Committees Report on Environmental Flow Rules for the Gwydir Valley. The RMC's rules aimed to provide continued opportunities for waterbird breeding, improvements in wetland vegetation as well as an increase in the breeding and migration of native fish. The rules were designed to benefit the wetlands of the valley.

In 2001, the Committee was asked to recommend sharing rules to form a statutory water management plan. A draft water sharing plan, with revised environmental flow rules, was prepared by the Committee and placed on public exhibition and gazetted in February 2003.

The environmental rules in the Gwydir Regulated River Water Sharing Plan are as follows:

Rule 1: Reserve all water above the plan extraction limit for the environment.

This means that on a long-term average basis, approximately 56% of yearly flows in the river are protected for the maintenance of environmental health.

Rule 2: Protect Low Flows.

Where tributary inflow downstream of Copeton Dam is less than 500 ML/d, pass flows through to the wetlands.

Rule 3: Off-allocation Limits.

Off-allocation extractions are limited to 50% of each flow event and off-allocation will not be declared unless flows exceed immediate water use requirements by at least 1,000 ML/d. The volume available to irrigation is calculated from the flow volume above this threshold.

Rule 4: Provide Water for Environmental Contingencies.

Each year a volume equal to 45,000 ML multiplied by the percentage allocation available to general security users is to be set aside for use in supporting bird breeding events.

What wetland specific or related issues are the current rules supposed to address?

The flow rules for the Gwydir were designed to address particular environmental issues. They include restoring the freshes and small floods that have been reduced as a result of river regulation and water abstraction, in order to provide adequate wetting of anabranches, effluents and riverine wetlands. This wetting in turn allows for the exchange of organic matter between the wetlands and the river as well as providing adequate habitat for wetland flora and fauna.

The Integrated Monitoring of Environmental Flow Rules

To assess the response of the riverine and wetland ecosystems of the Gwydir to the environmental flow rules, it was seen as essential that a sound scientific assessment of the rules be made.

The NSW Government established a major scientific program to address this need. This program is referred to as the Integrated Monitoring of Environmental Flows or IMEF. The environmental side of the program involves the collection of biological, physical and/or chemical data from river sites and wetlands within sections of the river that are affected by the flow rules. The program is designed to provide not only additional understanding of the flow responses of riverine ecosystems based on sound scientific methods, but also an opportunity to evaluate the environmental performance of the flow rules themselves. The IMEF program was implemented in 1997.

Monitoring is underway in the Gwydir Valley to assess the response of the river and associated wetlands to the environmental flow rules.

Under the IMEF program 5 wetlands in the Gwydir Valley are monitored for:

  • Hydrological regimes, inundation timing, volume, surface area, gauge height/depth, number of fillings, connectivity with the river (duration) etc
  • Aquatic Macroinvertebrates
  • Aquatic Plants
  • Frogs
  • Birds
  • Water Quality

What have the rules achieved so far?

The environmental flow rules have contributed substantially to the success of major water bird breeding events in the Gingham Wetlands.

The first water breeding event, in the summer of 1995/96, resulted from the flooding of more than 50,000 ha of the Lower Gwydir wetlands. For the first time in over a decade birds began to breed in the wetlands. It is estimated that around 60,000 birds, including egrets, ibises, spoonbills, herons, ducks, swans, pelicans, magpie geese, brolgas, bred in the wetlands as a result of this event.

Parent colonial nesting waterbirds are known to abandon their nests if water levels drop too low. When the flood waters started to recede in November of 1998, a release of about 300 ML/day from the ECA stored in Copeton Dam was made in order to maintain adequate water depth under the waterbird nests. This release allowed for the continuation of bird breeding in the wetlands. Counts of birds in November 1998 indicated that there were 15,000 breeding pairs of Ibis, 10,000 Egrets and 15, 000 Herons in the Lower Gwydir wetlands.

In the summer of 2003 a total of 5,100 ML of environmental releases were made which promoted wetland plant diversity. A further release occurred in summer of 2005 (a total of 13,395 ML) inundating 12 hectares of the Gwydir Wetlands and helping to sustain a major bird breeding event.