The enhanced Root Zone Water Quality Model (RZWQM2) can evaluate, manage, and improve water quality impacts of agricultural chemicals and other management practices; develop sus-tainable agricultural systems; and optimize lim-ited resources. The RZWQM2 is an advanced, but practical, model of root zone processes that influence water quality, soil water storage, effi-cient water use, and crop production.The benefits of RZWQM2 are that it provides users with a comprehensive, state-of-the-sci-ence, whole-system approach to evaluating man-agement effects on water (and soil) quality and production compared with simpler models that look at potential leaching of chemicals in isola-tion. It is unique in its emphasis on accurately simulating the effects of agricultural manage-ment practices on physical-chemical processes and plant growth, including the movement of water, nutrients, and pesticides through the crop-root zone to groundwater. The model allows the evaluation of management practices, such as no-tillage and residue cover vs. conventional tillage; rates, methods, and timings of application of wa-ter, fertilizers, manures, and various pesticides; and up to 100 years of different crop rotations. It also contains exclusive features of tile drainage and rapid transport of surface-applied chemicals through soil macropores to groundwater and tile flow. RZWQM2 was transferred to users through personal discussions, training sessions, and col-laborative testing/applications; updated ver-sions were delivered through the web. At users’ request, an international workshop was held in April 2004 to share experiences and discuss future collaborations to advance the applica-tions. During the past three years, the team has provided training to more than 40 users from the Environmental Protection Agency, the U.S. Geological Survey, and scientists internationally, and provided support to hundreds more. During this period, there have been 500+ downloads of the model. RZWQM2 is now being used by fed-eral agencies, industry, and numerous scientists in the U.S. and worldwide.