Bore Drain Rehabilitation withstands flooding

Bore Drain Reclamation and Rehabilitation project in the Moree and Boomi regions has successfully prevented thousands of tonnes of salt and minerals from being washed into the Murray Darling Basin river system by this year’s floods.

The $500,000 project was funded by the Border Rivers-Gwydir Catchment Management Authority (CMA) the NSW Office of Water and local landholders. The on ground earthworks were carried out by the NSW Soil Conservation Service.

Department of Primary Industries’ Soil Conservation teams from Narrabri and Warialda have completed a 3 year project to rehabilitate 600kms of saline bore drains that are no longer used to water livestock. This vast network of open bore channels has now been buried removing these salt laden scars from the landscape.

These structures ranged from relatively narrow drains to much wider channels several metres across. The soil on either side of the drains had to be carefully prepared and the earthworks and refilling of the drains carried out with technical precision to avoid future subsidence.

The artesian water that previously flowed through these drains for almost a century deposited huge amounts of salt and minerals pumped up from underground aquifers on to the land surface.

"If these open channels had been left exposed the flooding that has recently inundated Boomi, Moree and surrounds would have washed this salt and mineral pollution into the rivers systems of the Murray Darling Basin,” said Border Rivers-Gwydir CMA General Manager Paul Hutchings.

The bore drains had been essential infrastructure during the early years of agricultural development in many parts of north western NSW, providing reliable water for sheep and cattle in a dry landscape that otherwise could not have sustained a permanent livestock industry.

However in recent decades landholders have embraced Capping & Piping schemes that more efficiently utilise the precious water resource supplied by the Great Artesian Basin. The old style open bores with unrestricted flow have been plugged with concrete and replaced by new bore pumps that feed out water only as required.

Additionally the open dirt channels or bore drains have been replaced with fully enclosed pipes that reduce evaporation, improved water quality, and also allow for greater control of stock watering points. When livestock are moved off grazing areas troughs can be turned off, removing watering points for feral pests such as pigs and foxes.

Removing the open bore drains from the landscape is the final step in the Bore Cap & Pip revolution. Without this valuable rehabilitation process thousands of tonnes of salt and minerals left lying in these bore drains would have been swept into the river system by the recent flooding at Moree and Boomi.

Laurie Carrigan from “Newhaven” east of Boomi is part of the Boronga Bore Trust. Mr Carrigan says the rehabilitation project has made his farm more productive, “The bore drain had carried salty run off into one particular part of the property, so repeated inundation made this country unsuitable for farming. Now that the bore drain is gone we’ve been able to farm this area that was previously too saline to grow a crop.”

"If water from the big floods that we’ve just experienced had washed across the old bore drain and back into the river system, that water would also have been heavily contaminated by salts and minerals,” explained Mr Carrigan.

Despite the huge volume of water that inundated this region the rehabilitation earth works have withstood the floods and the old bore drains have remained safely buried along with their toxic salt load.

The rehabilitation earth works undertaken by the Soil Conservation teams at Narrabri and Warialda, and funded by the Border Rivers-Gwydir CMA, the NSW Office of Water, and landholders, will reduce the quantity of saline water leaving individual properties. “It will also improve the quality of the agricultural land within these areas, and provide improved surface water quality for both stock and domestic use,” said Larry Scott, Senior Operations Manager with the Gwydir Soil Conservation Service.

For further information about how the Soil Conservation Service can assist with rehabilitation earthworks on your property phone Head Office on 02 8836 5369, or contact your local office at Narrabri on 02 6799 6630 or Warialda on 02 6729 1227.

The Border Rivers-Gwydir CMA can also provide advice on improving the natural resources on your property including reducing salinity. To find out more contact your local CMA office at Moree 02 6757 2550, Inverell 02 6728 8020, Armidale
02 6773 5270; Glen Innes 02 6732 2998, or Goondiwindi 07 4671 4302.

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