This conference was stimulated by emerging demands to develop TMDL assessments for impaired water bodies. Over the last decade there has been a maturing of watershed science with new research findings and modeling approaches. These new solutions have resolved many of the problems that first faced watershed managers in dealing with TMDLs, but there are also emerging impediments to watershed assessments and achieving water quality goals. This fourth conference will look at emerging problems and new solutions to managing watersheds to meet water quality standards.