@Fisherman: Nuclear explosions underground aren't all that disastrous. Sure some radiation sticks around but it's pretty much stuck underground and whatever leaches into the drinking water won't be much more dangerous than the American mid-west because it dissolves into the water and averages out.
Colorado has several times more radiation just in the stones on it's surface than you'll find around your average nuclear power plant.
Even a direct hit by a nuclear bomb will only make the area unsafe for a short period of time, Hiroshima and Nagasaki aren't affected anymore.