Managed Aquifer Recharge (MAR)

Managed Aquifer Recharge (MAR) refers to storing water in natural underground aquifers when it is plentiful and available. If the water is left in the ground to revitalize a depleted groundwater system MAR is sometimes referred to as Aquifer Recharge (AR). The artificially stored water can also be recovered and used when it’s needed, a process called Aquifer Storage and Recovery (ASR). Using the natural properties of aquifers in any of these MAR scenarios can provide a variety of cost and environmental benefits and is an efficient water storage tool for municipal, agricultural and industrial users.

Municipalities typically use ASR to store winter surface water to supplement their water supply during peak usage periods, typically during drier summer months. When ASR well systems are designed correctly, they can be much more cost effective than surface reservoirs. Because aquifers are more resilient to disasters such as earthquakes and storm events, ASR is a valuable emergency water supply alternative. When surface reservoirs and source waters are affected by wildfires, flooding, or dam failures, water managers can fall back on their banked supply of groundwater.

In watershed projects and in depleted groundwater systems AR can become a way to restore declining groundwater levels and replenish water lost from storage for all users, and in other cases to recover lost baseflow to streams. As in ASR projects water can be diverted from streams during peak flows and introduced into shallow alluvial aquifers via infiltration ponds or ditches. If these high flows can be filtered to remove particulates they might also be injected into deep depleted aquifers via wells.

There are also industrial applications for MAR. In addition to acting as an efficient and safe reservoir, ASR can be an energy-efficient cooling or heating solution. Water stored in aquifers over the winter is cooler and stays insulated deep beneath the surface. Conversely, warm summer water can be stored and recovered during the winter for use in industrial processes requiring hot water or steam. In each scenario, ASR is an energy-efficient solution.

Whether it’s industrial, municipal or watershed projects—we help our clients evaluate the feasibility and potential of MAR. If conditions are favorable, we collaborate with water users to design and implement MAR programs. During permitting, we coordinate with regulators and the water user to permit and develop MAR monitoring and reporting programs that meet permit requirements and the owner’s needs.