Substantial growth in the hydrogeology field has occurred in response to federal regulations of the 1970s and 1980s dealing with water quality. The regulations led to increasing student applications, more universities offering programs in hydrogeology, and increased research support. With no new regulatory drivers and diminished perceived imminent threats to human health and the environment in recent years, the field of hydrogeology appears to have matured. An enormous amount of information, new technology, and new analytical tools have overwhelmed regulators and the regulated community. Although there appear to be many areas yet to explore, some of the more theoretical developments may be perceived by end users as having limited practical value or little immediate impact to solve existing problems. A key challenge is to put current theory and state of art technology into practice.