Traditional water resources management in the United States relies heavily on the use of centralized facilities, such as regional wastewater treatment plants and flood control reservoirs. Increasing concern for human impacts on aquatic systems and diminished federal support for large water management projects are motivating the increased use of small-scale, widely distributed practices, such as treatment wetlands and infiltration practices. These practices, which exploit or enhance natural systems and processes, can be used alone or in conjunction with traditional practices to enhance performance and reduce environmental impacts. The use of smaller, more distributed water management practices challenges the hydrological science community to improve its capacity for assessing and predicting hydrologic conditions and to make this capacity accessible to water resource practitioners.