Increasing water stress and decreasing supplies caused by growth and climate variability have expanded demand for managed aquifer recharge (MAR) projects to provide water supply resilience. Some of the most important factors in determining the performance of a MAR project include site selection, subsurface hydrogeologic characteristics and associated properties of the storage zone. Costs for invasive subsurface investigations to address these factors have slowly increased over the past two decades, with drilling costs increasing dramatically by as much as 30% or more since COVID‐19 hit, a result of supply chain issues, steel prices, and manpower challenges. This paper provides a high‐level review of major geophysical methods that have become more mainstream over the past decade or two to supplement invasive subsurface investigations and are very cost effective when compared to drilling boreholes and installing wells, which provide only point data. The more commonly used surface geophysical methods include ground‐based and airborne time‐domain electromagnetic methods (TEM), electrical resistivity, and seismic reflection. Airborne TEM methods (AEM) collect data very quickly, avoiding ground‐based access constraints, and land‐based methods are especially efficient using towed arrays. Electrical resistivity measurements provide resolution comparable to TEM but require more time than towed methods. Seismic reflection surveys are more expensive than other methods but typically have a much greater depth of penetration and can provide high resolution information on aquifer geometry, geology, and faults. Borehole geophysics is one of the more common methods used in MAR, providing near hole formation data and ground truths surface geophysics.

The Mexico City Metropolitan Area (MCMA) is a significant and important urban center in North America, covering an area of approximately 9500 km2 with a population of almost 23 million, yet the water supply remains unsustainable. The total water demand in the MCMA is 84 m3/s and is provided by groundwater (63% or 53 m3/s), imported water (27% or 23 m3/s) and recycled water (10% or 8 m3/s). The natural recharge of the MCMA aquifer is approximately 23 m3/s, indicating an overexploitation of groundwater resources of approximately 25 m3/s (800 Mm3 annually), a reasonable future goal for recharge in the MCMA. Hydrologic analysis indicates two main opportunities currently to increase water supply in the MCMA: indirect water reuse with recycled water and managed aquifer recharge (MAR) with storm water. An inventory of MAR project case studies in the MCMA summarizes methods for recharge, water sources, geographical distribution, and the main results obtained in each project for the last 80 years. The inventory consists of 21 MCMA area MAR case studies including (1) conceptual, (2) design level, and (3) pilot‐ to full‐scale facilities, only some of which have operated for relatively short periods of time, with one remaining MAR project currently operational. The review found that beyond the technical and economic issues that MAR project design normally address, the existing regulatory framework and the continuous change in water district chairs in charge of the operation and supply of water are significant barriers to increasing MAR in the MCMA.

Laboratory methods have improved dramatically during the past decade with much lower detection levels enabling some interesting results of human impact on the condition of the hydrologic system. Low levels of organic contaminants are present in surface and groundwaters throughout the nation.