Gwydir Valley environmental water
Lower Gingham watercourse inundated, autumn 2012. Photo: Daryl Albertson, OEH.
The Gwydir catchment covers 26,596 square kilometres, extending from the northern tablelands to the northern plains where it joins the Barwon River.
Managed environmental water is focused on the floodplain area west of Moree where the Gwydir River branches into three main systems:
- Gingham watercourse
- Lower Gwydir (Big Leather) watercourses
- Mehi, Mallowa and Moomin systems (south).
These areas contain a mosaic of wetland types from semi-permanent marshes and waterholes to floodplain woodlands which are only inundated during large floods.
Four wetlands in the Gwydir Valley are listed under the Convention on Wetlands of International Importance (the Ramsar Convention):
View a map showing the location of environmental watering areas in the Gwydir valley (Gwydirmap2013.pdf, 320KB).
The Gwydir wetlands are the Country of the local Gomeroi Aboriginal people, home of their heritage and important cultural sites. Over 160 cultural heritage sites have been recorded in the wetlands, including burial sites, scarred trees and stone artefacts. These wetlands were also known as a place of bountiful wild harvests.
Benefits of environmental water
Environmental water in the Gwydir Valley supports:
- wetland vegetation, including river red gum forests, river cooba, water couch marsh, marsh club-rush sedgeland and common reeds
- critical breeding and feeding habitat for colonial nesting waterbirds, such as egrets, herons, cormorants, spoonbills, ibis and darters
- critical habitat for other waterbirds, including ducks, swans, grebes, coots and swamphens
- habitat for migratory bird species listed under international agreements, including the barn swallow, black tern, Caspian tern, cattle egret and common tern
- habitat for native fish breeding and recruitment, including several threatened native fish species, such as silver perch, olive perchlet, purple spotted gudgeon and eel-tailed catfish
- the state’s largest stand of marsh club-rush sedgeland, listed as critically endangered under the NSW Threatened Species Conservation Act 1995.
Catchment condition 2012-13
The Gwydir Wetlands have experienced three consecutive seasons of widespread inundation in both extent and duration. Significant flooding in early 2012 stimulated a large colonial water bird breeding event, not seen since the late 1990s.
A succession of years of seasonal flooding was required to build and return resilience to a previously impoverished wetland system. Early results from field monitoring in 2013 indicate this flooding succession has moved the Gwydir wetlands to an improved state, particularly in relation to species diversity and abundance.
Available environmental water in 2013-14
Forecasts have identified a ‘moderate’ water year in 2013-14, with a wetter end to the winter period, which is likely to provide additional watering benefit to the wetlands, particularly during the cooler months of the year.
At the start of the water year, Copeton Dam was at 74% capacity, with high security allocations at 100% and general security licence holders having access to 107% of carryover entitlement. Approximately 208,640 ML of environmental water is available for use during the water year. This volume consists of NSW Environmental Water Holdings, Commonwealth environmental water and an Environmental Contingency Allowance provided under the Gwydir River Regulated Water Sharing Plan.
Environmental watering aims for 2013-14
The Gwydir Environmental Contingency Allowance Operational Advisory Committee (ECAOAC) has considered the previous three years of good watering outcomes and has recommended that deliveries this season will focus on restoring a natural flow pattern to Gwydir wetlands.
Water delivery may be triggered when natural flow events occur, which will allow the wetland system to continue to build resilience, maintain ecological health and current level of recovery.
A water delivery will also be made into Mallowa Creek wetlands and may occur into the Mehi River system in response to natural flow triggers. In the event of a dry year, water will be delivered to the core wetland areas of the Gwydir system.
For further information contact Justen Simpson, Senior Team Leader, Environmental Water Governance, NSW Office of Environment and Heritage: phone (02) 6229 7140.
Annual Environmental Watering Plan 2013-14
The Gwydir Valley Annual Environmental Watering Plan 2013-14 (130579GwydirAEWP.pdf, 2.3MB) outlines the environmental water scenarios in detail.
Environmental Water Advisory Group
The Gwydir Environmental Contingency Allowance Operations Advisory Committee (ECAOAC) advises OEH on managing environmental water in the Gwydir. The ECAOAC provides advice on the annual environmental watering plan and on specific managed environmental water releases during the year. The committee is chaired by the Border Rivers-Gwydir Catchment Management Authority.
OEH manages environmental water in the Gwydir catchment in partnership with:
Environmental water planning is supported by the following key documents and plans:
Reports on environmental water use
Environmental water use for 2012-13 is reported in Environmental water use in NSW: Outcomes 2012-13, which outlines environmental water scenarios in detail.
Page last updated: 13 March 2014