As many states expect continued drought in 2016 and beyond, the management of aquifers — underground geologic formations that retain groundwater — will be increasingly important, says the National Ground Water Association.
One potential tool to help provide for water when it is needed is called managed aquifer recharge (MAR). MAR captures available water during wet periods, during periods of low demand, or water that would be lost otherwise — then moves this water under controlled conditions into underground geologic formations called aquifers.
“MAR will become an increasingly important tool for mitigating the economic, environmental, and public health impacts of water shortages,” said William Alley, Ph.D., NGWA's director of science and technology. NGWA has published an information brief, as well as a best suggested practices document, on the subject.
“Integrating MAR into the nation's water infrastructure will require proper siting selection, design, construction, operation, and maintenance, but it can be done,” Alley said.
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 and, of course, all available water
- 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
- 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 (California) Water District; Central Arizona Groundwater Replenishment District; the Peace River Manasota Regional Water Supply Authority (Florida); United Water Resources (Idaho); Rio Rancho, New Mexico; and Dayton, Ohio. There are hundreds of such projects in place across the nation.
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 percent of community water systems and many individual households with an independent source of water use groundwater. Also, groundwater is the source for 42 percent of the nation’s agricultural irrigation water. Groundwater also feeds streams and rivers, especially during periods of drought or low flow, providing environmental benefits and sustaining ecosystems.
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