Two of the main primary branches of the Colorado run through Colorado Springs, home of the Cheyenne Mountain complex.
Wrong side of the Continental Divide. The Colorado River drains the Western side of the Continental Divide.
http://en.wikipedia.org/wiki/Colorado_River
The other Colorado River that is in Texas, and not part of this game, does not even go through Colorado. The word Colorado refers to the color of the water from the minerals it picks up.
http://en.wikipedia.org/wiki/Colorado_River_(Texas)
The river that does drain the Colorado Springs area is the Arkansas River, but that goes East to the Mississippi River.
http://en.wikipedia.org/wiki/Arkansas_River
Now, the Colorado River does drain a large part of the SW United States. There are some uranium mines but little else of major strategic value in the drainage. Even mines would not be targets as the process to get uranium ore to something that can be used in a bomb is long and complicated. The issue of being able to make more bombs is moot after the first nuclear exchange. I doubt if the area would have been hit with many bombs. So, it is hard to say how radiated the water would be.