Cost wil be based on if the house has been rezoned into a flood plain or not. The Sac Valley was just re-evaluated and many places have been rezoned as flood plains, which their insurance will go up accordingly in 2 yrs.
If it flooded in '97 during the New Years Pineapple Express that flooded Reno, Truckee, and other mountain/foothill communities, but hasn't been flooded at any other times in its history, the flood insurance may not be that much, since that was an unusual occurrence. Check w/an insurance company and see what the premiums will be and wether or not it is now considered to be a flood plain. If the premiums are going to double/triple in 2yrs, you will want to look for another house on higher ground.