A new policy has been developed on managed aquifer recharge (MAR) to aid the approval of socially and environmentally acceptable MAR proposals under the Rights in Water and Irrigation Act 1914.
The draft MAR policy was released for public comment in October 2009 and finalised in January 2011. It generated significant interest, with 17 submissions received from a range of interest groups, including government, research institutes, water service providers, consultants and the mining and development sectors.
The policy describes the water quantity and water quality issues relevant to MAR, and how they will be managed by the department. It also outlines the process for licensing MAR schemes and includes general information required to support licence applications.
It has been developed in line with the National Water Initiative, which supports greater innovation in the use of water resources for the benefit of the community and the state.
MAR is already being undertaken in Western Australia, through projects such as reinjection of dewatering excess at mine sites and reuse of treated wastewater for irrigation. There are also several MAR projects being planned, including irrigation of public open space using harvested stormwater; infiltrating treated wastewater for environmental benefit; and a trial to inject highly treated wastewater to supplement drinking water supplies. The policy provides specific examples of MAR schemes in Western Australia and outlines the key management requirements for these.
What is MAR?
MAR is the purposeful recharge of an aquifer under controlled conditions to store the water for later abstraction or to achieve environmental benefits.
Water can be added to the aquifer by infiltration (via structures such as ponds, basins, galleries and trenches) or injection via wells.
There are many potential sources of recharge water including stormwater (excess or redirected), treated wastewater and water from watercourses or aquifers.
Some pre-treatment of the source water may be required before recharging the aquifer to ensure that the quality of the groundwater is maintained or improved. The level of treatment required, if any, will generally depend on a risk assessment.
Benefits of MAR
MAR schemes have the potential to increase water availability by generating water supplies from sources that may otherwise be wasted. It can provide environmental, social and economic benefits.
Benefits include improved maintenance of wetlands and caves, opportunity for storage of water (in times of surplus to meet need in times of demand), prevention of salt-water intrusion, increased water availability for irrigation use and augmentation of drinking water supplies (known as groundwater replenishment).
MAR also has the potential to improve water quality through natural processes. It may assist in the removal of nutrients such as phosphates and organics, the degradation of chemicals (such as disinfection by-products) and pathogen die-off.
Limitations of MAR
MAR will not be feasible everywhere, due to hydrogeological, environmental or cost constraints. In some cases where stormwater or treated wastewater is considered for irrigation or other non-drinking purposes, direct use of the water could be preferable to MAR.
There is potential for MAR to play an important role in the sustainable management of Western Australia’s water resources, however there are a number of environmental, health and social issues associated with the process that need to be addressed. The MAR policy provides some guidance on these issues and directs proponents to other agencies where appropriate.
Regulatory requirements
The MAR policy provides details on the Department of Water's requirements for MAR schemes. The role of other agencies is also outlined.
The Department of Water coordinates the across agency approval process for non-drinking water schemes through the Draft approval framework for the use of non-drinking water in Western Australia. These schemes may involve MAR or other mechanisms such as third pipe or direct application.
Where stormwater or treated wastewater is the source water for MAR, the MAR policy refers to the Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2) – Managed Aquifer Recharge (July 2009). The guidelines assist in managing any associated health and environmental risks and will assist in determining how MAR can be used as a sustainable means of water management.
Would you like more information?
If you have any questions on the MAR policy, please contact Yvonne Thomson or Tim Katsavounidis in the Water Licensing Policy section of the Department of Water (6364 7600).
For more information on MAR, visit the CSIRO Water for a Healthy Country website or for more information on Groundwater Replenishment visit the Water Corporation website.