Depends on if you want to gamble. 9 out of 10 will not get sick. Do you want to be the one and ruin your hunt? I got giardia in New Mexico at around 9,000 ft. It absolutely knocks you down.

If you are in an area like bigbulls described, you probably will do as the Romans do and enjoy the fresh water. But if you don't know where you might wind up, take iodine. Tastes bad, but when I'm thirsty I don't mind it a bit - especially when I recall my bout with giardia.