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Wetlands

Macquarie Valley

Includes the Castlereagh, Cudgegong & Bogan Catchments

Introduction
Wetlands of the Macquarie Valley
Feature on the Macquarie Marshes
Environmental Flow Rules

Introduction

The Macquarie and Cudgegong Rivers form a complex system that delivers water for industry, agriculture, recreation and domestic use, while supporting natural processes and significant wetland systems. The Macquarie Marshes, located at the bottom end of the Valley, are not only one of the largest semi-permanent wetlands in south-eastern Australia, they are also internationally important.

Wetlands of the Macquarie 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.

Macquarie Marshes Nature Reserve & Wilgara Wetland (See F on Map 2)

The Macquarie Marshes Nature Reserve was accepted as a Ramsar site in 1986. The Wilgara wetland near the Nature Reserve was accepted as a Ramsar site in 1999. The combined area of the wetlands is 18,726 ha. They are located in the central west of NSW. The wetlands, are actually part of the larger Macquarie Marshes wetland, which has an area exceeding 250,000 ha during major flooding. The wetlands contain the largest area of reedbeds in south-eastern Australia, and one of the largest River Red Gum (Eucalyptus camaldulensis) woodlands. The Marshes are important for waterbirds, iand support large numbers of herons, ducks, egrets, ibises, spoonbills, terns and migratory waders. Agricultural development, in particular irrigation, is the main human use of surrounding land.

Macquarie Marshes
Source: DLWC

Environmental Flow Rules

Their Relevance to the Wetlands of the Macquarie Valley

The river systems and their associated wetlands and floodplains have changed significantly from their natural state and there is evidence of increasing environmental stress within the system. For example, changes in flow volume and seasonality have led to a decline in breeding opportunities for wildlife populations and increased frequency of algal blooms.

The Macquarie was the first catchment in NSW to have environmental flow provisions included in its river management arrangements through the Macquarie Marshes Water Management Plan 1986. The plan was reviewed and published in 1996.

In late 1997, a River Management Committee was established to further examine the environmental flow rules and its recommendations were implemented in 1998/99. A statutory water sharing plan for the Macquarie and Cudgegong Rivers commenced in July 2004. The environmental rules in the plan are:

All flows above the Plan extraction limit are reserved for the environment
- This means that, on a long-term average basis, approximately 73% of yearly flows in the river are protected for environmental health.
Provide more natural flows in the upper reaches of the Cudgegong River
- Release a portion of inflows to Windamere Dam to attain, in combination with any downstreamtributary inflows, flows between 150 and 1,500 ML/day at Rocky Water Hole.
- Releases will not be made when the storage level of Windamere Dam is equal to or less than 110,000 ML.
- Releases will be subject to an annual limit of 10,000 ML.
Establish an environmental water allowance for the Macquarie River
- Up to 160,000 ML may be credited to the environmental water allowance in any water year.
- Part of this environmental water allowance (sub account 1) is to be released to provide more natural flows downstream of Burrendong Dam during the periods 1 June to 30 November, and 15 March to 31 May each year.
- The other part of this environmental water allowance (sub account 2) is to be released when needed to enhance opportunities for native fish recruitment and dispersal, to ensure completion of colonial water bird breeding and to alleviate severe, unnaturally prolonged drought conditions in the Macquarie Marshes.
- An Environmental Flow Reference Group is to advise when the water should be released for environmental purposes.

What wetland specific or related issues do the rules address?

The outcomes from the environmental flow rules include:

The provision of a more natural flow regime;
The restoration of some critical portions of the natural flow regime to target the health of the river as a whole;
A reduction of the incidence of conditions that are favourable for algal blooms;
Improvement in the overall health of the Macquarie Marshes and the lower reaches of the river;
An increase in the frequency and success of bird breeding events in the Macquarie Marshes; and
Increasing food and habitat availability.

The Integrated Monitoring of Environmental Flow Rules

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

The NSW Government has implemented the Integrated Monitoring of Environmental Flows or IMEF program since 1997. 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 provides 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. Monitoring is under-way in the Macquarie Valley to assess the response of the river and associated wetlands to the environmental flow rules. Twelve wetlands 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?

Monitoring of the effects of the 1996 Macquarie Marshes Plan in 1997, indicated that the rules were successful in delivering an additional 18,750 ML to the Macquarie Marshes above that which would have occurred prior to the introduction of the flow rules. The flows were also delivered in such a way as to maintain the natural and necessary drying patterns in the Marshes.

There were also positive results from the environmental flow rules in the 1998/99 season. The additional water provided to the Macquarie Marshes, combined with widespread flooding led to spectacular bird breeding, revitalisation of floodplain eucalypts, River Red Gums, Black Box and Coolabah, and a significant improvement in the amount and quality of water leaving the marshes.

During the 1999/2000 season there were 6 releases of the Wildlife Allocation, which delivered a total of 136,980 ML to the Macquarie Marshes. Environmental flow releases totalling some 84,000 ML were made into the Marshes from November 2005 to January 2006 to support water bird breeding and hundreds of water birds were still present some months later.