Managed aquifer recharge captures available water and moves it under controlled conditions into aquifers
s many states expect continued drought in 2016 and beyond, the management of aquifers—underground geologic formations that retain groundwater—will be increasingly important, according to the National Ground Water Assn. (NGWA).
Managed aquifer recharge (MAR) captures available water during wet periods, during periods of local demand, or water that would be lost otherwise—then moves this water under controlled conditions into underground reservoirs called aquifers.
“MAR will become an increasingly important tool for mitigating the economic, environmental, and public health impacts of water shortages,” stated NGWA, which has published an information brief on the subject. “Such projects are occurring in every region of the country. Properly sited, designed, constructed, operated and maintained MAR projects are a key component for addressing the nation’s water supply challenges.”
MAR projects are used to:
- Provide more stable water supplies during drought;
- Mitigate land subsidence, where depleted aquifers collapse resulting in a dropping of the ground’s surface;
- Supplement the quantity of groundwater available;
- Conserve and dispose of runoff and floodwaters;
- Reduce or eliminate declines in the water level of groundwater reservoirs;
- Reduce or halt saltwater intrusion;
- Improve groundwater quality;
- Store water in off-seasons for use during the growing seasons; and
- Allow stored water to be released during dry periods to augment minimum streamflows and maintain lake levels, thereby benefiting ecosystems.
Successful MAR projects include ones operated by the Orange County (Calif.) Water District; Central Arizona Groundwater Replenishment District; the Peace River Manasota Regional Water Supply Authority (Fla.); United Water Resources (Idaho); Rio Rancho, N.M.; and Dayton, Ohio.
One reason the potential of MAR is so great is because of the magnitude and importance of groundwater to the nation’s water resources. About 78% of community water systems and nearly all rural water supplies use groundwater. Also, groundwater is the source for 42% of the nation’s agricultural irrigation water. Furthermore, groundwater feeds streams and rivers, especially during periods of drought or low flow, providing environmental benefits and sustaining ecosystem services.