Hinds/Hekeao managed aquifer recharge trial completes third year of operations

The Hekeao / Hinds Managed Aquifer Recharge (MAR) Project has recently concluded its third year of operations. During the third year of operations, the Project has increased the number of active recharge sites from one to twelve and increased the annual recharge volume from 1.85 million cubic metres to 6.15 million cubic meters. 

What is MAR? And how does it work?

Infiltration basins, which act like big leaky ponds, are filled with high-quality clean water which seeps down and recharges the groundwater.

Clean alpine water from the Rangitata River is delivered to the MAR site via irrigation races and pipes.  The silts carried by the water settles in the forebay before the water is allowed to flow through to the main infiltration basin.  From there, the clean water seeps down to recharge the groundwater system.

The entire surface and groundwater system is carefully monitored for water quality, quantity and ecological health.  Water is not recharged during times of significant rainfall to reduce the risk of lowland flooding.  Likewise, when there is a high demand for water, recharge operations cease.

What are the goals of the Project?

  • Target and protect drinking water supplies;
  • Enhance groundwater quality;
  • Improve baseflows to spring-fed streams and rivers for ecological, cultural and social values; and
  • Improve and sustainably manage groundwater levels.

What are the results telling us? 

The project has increased the annual recharge volume from 1.85 million cubic metres to 6.15 million cubic meters. 

The intensive monitoring near the Pilot Site shows that MAR influenced groundwater is being managed at low nitrate-nitrogen concentrations (1-3 parts per million) and groundwater levels remain sustainably high, even following moderate shutdown periods.

A preliminary Business Case has also been completed by the Hekeao Hinds MAR Governance Group to inform community conversations regarding the potential long term role for MAR in the Hekeao Hinds Zone and how this could be funded. The Hekeao Hinds Water Enhancement Trust has recently been formed to take over responsibilities from the Governance Group, including the completion of the Business Case and the continuation of the community conversations.