Human activities alter the environment of a river basin through land use choices such as road building and urban sprawl. Land use and land cover change reflects the interaction between natural and human systems. To better understand the complexity that arises from the interaction of the two systems and their interrelationships, this project will conduct an assessment of changes over the last twenty years on the Blanco River basin in Texas as it relates to social economic conditions in the region. A decision support system that couples a land use change simulation model, a surface flow and sub-surface flow simulation model, and a non-point source pollution simulation model will be developed for the Blanco River watershed in Texas. The outcome of the land use change modeling will provide temporal and predictive information on urban growth and historical land use patterns in the area that will then be used as inputs for the hydrological impact simulation model. The ultimate goal for this research project is to provide scientific information that regional resource management planners in the area can use to optimize the use of the land to ensure that an ecologically sustainable water supply is maintained.