In America, as in most countries in the world, the challenges of supply and demand for water keep a strong focus on the critical role of groundwater-resource management. Strategies to conserve, recharge and structure withdrawals have not only become more sophisticated but are increasingly connected to wider hydrological and environmental issues. Regulatory measures for drinking-water supply and for environmental restoration impose new challenges for water managers and their hydrogeological advisors. The causes (drivers) of trends in American hydrogeology include factors such as water scarcity, climate uncertainty, energy costs, carbon footprint concerns, ecological requirements and new concerns about contaminant concentrations greater than human-health thresholds.