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Wetlands

Namoi & Peel

Introduction
Wetlands of the Namoi Valley
- Wetlands of National Importance
Environmental Flow Rules

Introduction

Water from the Namoi 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 the source of millions of dollars in agricultural exports for Australia. Water from the Namoi also supports natural processes and important wetland systems.

The Namoi River

Wetlands of the Namoi Valley

The wetlands of the Namoi Valley have a range of uses including boating, water skiing, swimming, fishing, yabbying and bird watching. One of them, Lake Goran, is listed under the Directory of Important Wetlands in Australia.

Sunset over a large lake in the Namoi Valley

Wetlands of National Importance

The following wetland summary has been adapted from the Directory of Important Wetlands in Australia, 3^rd 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.

Lake Goran (Wetland No. 5 on Map 2)

Lake Goran is located on the floodplain of the Namoi River, approximately 30 km south of Gunnedah. It is a large internal drainage basin covering more than 6000 ha when full, making it the largest natural waterbody in the Namoi Valley. The lakebed is privately owned and when dry is used for cropping, with only small areas which are regularly waterlogged (< 10 %). It is also commonly used for grazing, fishing and occassionally swimming.

The lake provides substantial waterbird habitat when filled and may act as a drought refuge if this coincides with a dry season in the more western areas. The ephemeral nature of Goran Lake suggests that the wetland would be highly productive when filled after a dry period, providing a good supply of food for wetland biota, including waterbirds.

The Freckled Duck (Stictonetta naevosa) which is listed as vulnerable under the NSW Threatened Species Conservation Act 1995 has been recorded within Lake Goran (NPWS, 1998b). The White-bellied Sea Eagle (Haliaeetus leucogaster) which is listed under CAMBA has also been recorded at the Lake (NPWS, 1998b).

Environmental Flow Rules

Their relevance to the Wetlands of the Namoi Valley

Over the last 100 years, the Namoi River, its wetlands and floodplains have changed significantly. In more recent times the building of dams and the growing use of water for irrigated agriculture have contributed to these changes. This development now makes up a major component of the Valley's economy and contributes substantially to the prosperity of the general community as well as individual farmers. However, there is clear and increasing evidence of the problems that increased water use is causing to the health of the waterways, wetlands and billabongs of the Namoi Valley.

In late 1997, a River Management Committee (RMC) was established for the Namoi, as part of the statewide water reform process to recommend to the Government a set of Environmental Flow Rules (EFRs). Click here to view a PDF of the River Management Committees Report on Environmental Flow Rules for the Namoi Valley. EFRs were agreed to by the Committee, endorsed by the Government and introduced in the Namoi Valley for the 1998/99 water year. In 2001 the Committee was asked to advise on the rules for a water sharing plan for the Upper and Lower namoi regulated rivers. The plan commenced in July 2004 and includes the following environmental rules:

Rule 1. 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.

Rule 2. Protect end of system flows
Minimum flows are maintained in the Namoi River at Walgett during the months of June, July and August, to reflect those that would have occurred naturally. This rule does not apply when the total water stored in Split Rock Dam and Keepit Dam is less than 120,000 megalitres.

Rule 3: Protect high uncontrolled flows
The limits to total extractions by all supplementary water access licences in the Lower Namoi (during periods when flows are above specified flow levels) also provide environmental benefits. In particular they:

protect important rises in water levels,
maintain wetland and floodplain inundation, and
maintain natural flow variability.

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

The flow rules for the Namoi were designed to assist in achieving:

healthier instream and riparian vegetation leading to greater streambank stability;
better habitat for fauna;
suppression of algal blooms;
improved flows in the Barwon-Darling;
better water quality;
discouragement of alien pest species, particularly carp; and
maintenance of flow variability along the river.

The Integrated Monitoring of Environmental Flow Rules

To assess the response of the riverine ecosystems of Namoi 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 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 under-way in the Namoi Valley to assess the response of the river and associated wetlands to the environmental flow rules Under the IMEF program 5 wetlands in the Namoi 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 will the rules achieve?

The rules ensure that a proportion of the high uncontrolled inflows are protected from extraction to assist with inundation of wetland areas.