One of the great features about InfoSWMM, InfoSewer and InfoWater from Innovyze is the intimate connection between your model data and your GIS data. It is important for this to work correctly that you use the correct spatial reference. Innovyze has many tools for changing the spatial reference:
1. Arc GIS TOC
2. Arc Toolbox projection tools
3. Innovyze tools for changing the spatial reference
4. Innovyze tools for margining spatial reference
5. GIS background maps from ESRI
6. Google Earth and Google Maps connections