Managed Aquifer Recharge (MAR) is an increasingly important water storage and supply management strategy, alongside demand management, to secure reliable water supplies while replenishing stressed groundwater systems and protecting water quality. MAR can be defined as the purposeful recharge of water to aquifers for subsequent recovery or environmental benefit. In the 50 years from 1965 to 2015, global MAR capacity has grown from 1000 to 10 000 GL/year (Dillon et al 2019). There are many examples from around the world that demonstrate the advantages of MAR (Ross and Hasnain 2018).

The USA accounts for 26% of the reported global MAR capacity. Annual average MAR in the US has grown from at least 302 GL in 1961-70 to at least 2569 GL in 2011-2015 . California accounts for over 70% of reported US recharge capacity, Arizona accounts for 20% and other states, notably New York, Florida and Texas, make up the remainder. Most of the reported recharge capacity is in infiltration basins (Dillon 2018). Although the majority of the MAR schemes in the US have been set up to secure urban water supplies, there are examples of well-established MAR schemes dedicated to supplying water for agriculture and irrigation

This report reviews four selected agricultural MAR case studies from the US and one from Spain, analysing key factors contributing to the feasibility and sustainability of each MAR scheme. These schemes have been selected to represent different MAR scales and technologies. The five schemes are the Arizona water bank, Kern water bank California, Kings River California, Central Platte Natural Resources Management District and the El Caracillo scheme in Spain. A summary of these schemes is given in Table 1.

The first part of the report contains an overview of each case study and factors affecting project feasibility and sustainability. The second part of the report includes further details and analysis of each case study including:

• objectives and evolution;

• physical feasibility; sources of water and recharge arrangements;

• financial and economic feasibility;

• impacts on third parties and the environment; and

• governance, legislation and policies.