Berkeley Law

Groundwater sustainability depends on balancing aquifer inflows and outflows. Extraction (pumping of groundwater, typically for human use) and recharge (inflow of water to an aquifer from the land surface and streams) are central components of this water balance. Often, increasing demands for groundwater are exacerbated by stresses on limited surface water supplies. Changes in land use and shifting climate can result in less infiltration of precipitation into the ground, reducing recharge. Increasing water scarcity has led to increased pumping, and in turn, unsustainable management of groundwater in many basins, resulting in depleted supplies, degraded water quality, and other impacts. Conservation strategies have reduced demand in some basins, and there are also opportunities for increasing recharge; both strategies can help to tip the water balance towards sustainability. Natural recharge occurs across the landscape, in forests and fields, and below rivers and streams; it is a fundamental hydrologic process that is difficult to measure or control because it varies so greatly in location and timing. Managed aquifer recharge (MAR) is a set of techniques used to improve groundwater conditions by routing more surface water into aquifers. MAR can be applied at many scales, from street corner swales to regional systems. MAR based on the distributed collection of stormwater (“distributed MAR”) can be accomplished at an intermediate scale, generating hundreds to thousands of acre-feet/year of infiltration benefit. The promise of distributed MAR stems from its modest cost, and comparative simplicity of design and operation. Distributed MAR projects can be developed on private or public land across a groundwater basin, potentially generating more total benefit than smaller scale installations, and with less cost and complexity than regional MAR systems. A key challenge for developing distributed MAR projects lies in creating incentives that will motivate landowners, tenants, and other stakeholders to participate. Distributed MAR projects can be funded by a limited number of private participants, but public benefits may accrue more broadly. Developing and implementing policies to encourage the creation and operation of distributed MAR systems is a challenge at the frontier of groundwater management.