Global challenges have exacerbated a search for solutions to poverty and environmental degradation. Integration it was argued would help address the twin challenge. Integrated Water Resources Management (IWRM) was supposed to be that magic bullet and was embraced by scientists because of the clinical efficiency with which it argued for integrated analysis of sectors and resources and of systems and scale conditions. This paper argues that effective implementation of the Water-Energy-Food (WEF) Nexus can be supported by robust science. The corollary that robust science automatically leads to effective implementation is not always known to be true. The nexus approach sheds light on the challenges of implementation by introducing concepts of trade-offs and thresholds and consequently emphasizes the importance of transdisciplinary approaches to sustainable development.