Agriculture is a significant part of California’s economic engine. It accounts for $100 billion in agriculture related business each year. Given California’s Mediterranean climate, large-scale managed aquifer recharge (MAR) is a critical element of sustainably managing water resources in California’s agricultural heartland. Conjunctive management of surface water flows in the Salinas and Kings River drainages, two of the most vital agricultural areas in the State, has been used for many years to augment natural recharge of the important underlying aquifers. Additional projects are being implemented to increase recharge efforts to offset overdraft conditions using excess river flows. Three examples of large scale managed aquifer recharge are examined: 1) an existing and well-studied MAR program in in the Salinas River valley that coordinates reservoir releases to optimize groundwater recharge along the Salinas River in Monterey County; 2) a relatively new water bank along the upper Kings River that recharges seasonal excess flows using an old river channel; and 3) the planned use of agricultural fields to recharge flood flows along the lower Kings River.
The objectives and operation of each MAR system are evaluated and their overall benefit on underlying groundwater storage conditions is examined. The importance of stakeholder involvement, systematic data collection and analysis, and the potential of climate change are discussed. Benefits and challenges for each example are examined along with key criteria in the selection and design of large-scale MAR programs.