I haven't seen projections specificallyfor the Colorado Basin (but haven't looked). But there are some really interesting results based on climate projections for the the Sierra mtns and Pacific Northwest. Check Web of Science for pubs by Dettinger and Cayan, or email me at [email protected]
and I can send you some stuff.
If you're really focussed on the Colo Basin, I can give you the names and coordinates of some people that will know about this. The climate models are suggesting that in the continental US, hydrology in the far west and northwest will be most impacted by rising temperatures.