I love Idaho. The Middle and Main Stem of the Salmon River are two of my favorite rivers. Hells Canyon is superb too (you have been hiking up in the Seven Devils Wilderness, haven't you?). If no, you need to change that sometime soon.
Since I enjoy visiting Idaho, I decided to list all the Idaho calendars I've been able to discover. However, similar to Montana, there are few calendars specifically about Idaho available. But the ones I've found are shown below.
Click any of the links or images for more information about each calendar. All calendars available throug Amazon.