BBSW - Overview

Snapshot

Located 30km north-west of Griffith, NSW, and spanning 3,200 hectares, Barren Box Storage and Wetland (BBSW) project is one of the largest water infrastructure projects in regional Australia specifically instigated to return water to the environment. The major outcomes for this project are:

  • reduced water evaporation and forced releases to the lower Mirrool Creek floodway, saving an average annual 20,000 megalitres which will be returned to the Snowy River without impacting on any irrigator's entitlements
  • significant benefits for the environment through the restoration of more natural flow regimes to the site and return of flows to the upper reaches of the Snowy River, as well as reducing drainage to the lower Mirrool Creek environment
  • improved management and efficiency of the water storage and reduction in downstream flooding
  • improved water quality for downstream users (Wah Wah Irrigators)
  • preservation and enhancement of local sites of indigenous cultural significance
  • the generation of considerable social and economic benefits for the local community by ensuring the continuation of sustainable irrigation in the Murrumbidgee Irrigation Area (MIA)


Barren Box History

Barren Box is a large shallow depression on Mirrool Creek. In its natural state, Barren Box was an intermittent wetland, consisting of a Black Box woodland and lignum shrubland and only contained water for short periods of time after excess rainfall.

During redevelopment of the site, artefacts were unearthed and identified as belonging to the Wiradjuri Aboriginal tribe. Carbon dating identified some artefacts to be 450 years old, thereby indicating the significance of Barren Box as an important meeting place for the Wiradjuri people. The Wiradjuri tribe is also known as 'the river people' as they lived along the banks of the Lachlan, Macquarie and Murrumbidgee Rivers. Murrumbidgee is the only river out of the three to retain its Aboriginal name and is Wiradjuri language for 'plenty water or big water'.

Following European settlement and the opening of the Irrigation scheme in 1912, Barren Box flooded periodically until the late 1950's, after which it became permanently inundated, creating an artificial lake system and permanently altering the natural ecology. This change came due to the increased development of land and irrigation.

Barren Box is the major reuse point for the MIA, supplying water to the irrigation districts of Tabbita and Wah Wah. Whilst providing a necessary water storage facility in the MIA (80,000 ML at full supply level), the large shallow surface area of approximately 6km in diameter, resulted in significant evaporation losses and offered little operational flexibility.

Surrounding communities were quick to realise the recreational values of Barren Box and for decades enjoyed visiting the swamp for fishing, camping, family picnics and field and game purposes. With the outbreak of Alligator Weed, a 'Weed of National Significance' (WONS), duck shooting ceased in 1994 to reduce the risk of spreading this weed by vehicles entering and leaving the site. Thankfully, birdlife populations are today viewed as an ecological asset.

Click on the following: Map of MIA area (pdf 347kB); BBSW_2002-pre-development (pdf 516kb).


Project Background

The Snowy Hydro Scheme is an integrated water and hydro-electric power scheme, collecting and storing water that would normally flow east to the coast and diverting it through trans-mountain tunnels and power stations and then releasing it into the Murray and Murrumbidgee Rivers for irrigation.

The Snowy Water Inquiry was commissioned by the Commonwealth, Victorian and New South Wales Governments in 1998 with a brief to recommend environmental water options to compensate for the Snowy Hydro Scheme. The agreed outcome of the Snowy Water Inquiry (Heads of Agreement) was to increase environmental flows to the Snowy River and Murray River to 21% of natural flow.

On the basis of the Heads of Agreement, Murrumbidgee Irrigation explored options for water savings projects in order to ensure the sustainability of the MIA and avoid the potential for the removal of water entitlements. Murrumbidgee Irrigation proposed that 20,000 ML/year of water could be saved and returned to the rivers from reconfiguration of the site.

The idea of improving the efficiency of the shallow basin by splitting it into more efficient and useable cells was first raised in 1992 by the company. However, at the time, the cost was deemed uneconomical for the benefits to be gained. In 1998, as a result of the Inquiry, it was proposed that the water savings could be sold to the NSW Government to be returned to the Snowy River for environmental flows, thereby offsetting the cost of the project.

Redevelopment Works

In 2001, planning commenced to improve the operating efficiency of the storage and to restore the majority of the site to its natural wetland state. In June 2005, the NSW Government approved the $29 million redevelopment of Barren Box and construction commenced in October 2005.

The site was divided into three basins, including two sites for water storage and the third site (over 50%) returned to wetland rehabilitation. This was achieved by the construction of two levee banks installed through the existing storage site totalling 10km in length and a maximum of 5 metres in height.

The project involved:

  • constructing an 'active' storage cell, volume of 24,500 ML, 1,230 ha (40%)
  • constructing an 'intermediate' storage cell, volume 4,500 ML, 320 ha (10%)
  • preserving 50 per cent of the site to a natural ephemeral wetland - 44,000ML 1650 ha (50%)
  • widening the Wah Wah Main Channel
  • constructing a 2,000 ML en route storage adjacent to Bray's Dam on Mirrool Creek, which will deliver significant water savings in its own right

Click here for an aerial image of BBSW in 2006 (pdf 519kb) following redevelopment, and showing water in the intermediate cell.


During the redevelopment of Barren Box and the construction of the en route storage at Bray's Dam:

  • 800,000 cubic metres of earth was moved
  • 42,000 cubic metres of rock and gravel placed
  • 14,000 cubic metres of sand was used in the seepage cut-off filter

Click here for an aerial image of Bray's Dam-Jan 2006 (pdf 523kb).

The reconfiguration and structural works at Barren Box and Bray's Dam focused on improving the efficiency of two key aspects of MIA's water supply, drainage and recycling system:

  • reducing evaporation through smaller, more responsive storages
  • improving the ability of the drainage system to capture and reuse excess system flows from Mirrool Creek upstream of Barren Box


Project Funding

Murrumbidgee Irrigation funded construction activities for the $29 million works program. This is a significant investment by our company and clearly demonstrates our commitment to improved environmental management at local, regional and national levels and to improve our level of service to customers and shareholders.

Water for Rivers has purchased the water savings generated and will use it as environmental flows in the Snowy River. Water for Rivers is a joint initiative of the Commonwealth, NSW and Victorian Governments established in 2003 to achieve significant improvements in environmental flows, into the Snowy River and the River Murray.

The official commissioning of BBSW took place on 11 August 2006, on site with the Hon. Ian Macdonald, Minister for Natural Resources, Primary Industries and Mineral Resources presiding over proceedings. Government officials, Wiradjuri representatives, the media, surrounding farmers and a vast array of people involved in the project celebrated its completion overlooking the stunning view of the intermediate cell with the returning birdlife putting on a spectacular performance. The project is an example of how potentially competing parties can work together to achieve mutually beneficial outcomes.

From left: Richard Bull, The Hon. Ian Macdonald, and Dick Thompson. (Earthcraft Photography)


Awards

In September 2006, Murrumbidgee Irrigation along with the project consultants URS Australia Pty Ltd were awarded the prestigious Environment and Heritage Award for the Barren Box Storage and Wetland redevelopment project at the Sydney 2006 Engineering Excellence Awards.



Photo of both storages (Earthcraft Photography)

The Environment and Heritage Award was a strongly contested category with six finalists vying for the honour of being the Sydney winner. The Award recognises projects that deliver direct positive benefits to the environment or conservation, with ecological sustainability being an integral part of this category. Barren Box and other outstanding projects selected from the 2006 Engineering Excellence Awards were displayed at Sydney's Powerhouse Museum for the whole of 2007.

The BBSW project was also Runner Up in the Engineering for Regional Communities Award, only being surpassed by the visually inspiring Sea Cliff Bridge which forms part of Lawrence Hargrave Drive on Sydney 's south coast.