If you start your search at Creative Commons, you can immediately narrow it down to people that have already approved their photos for other uses.
http://search.creativecommons.org/
Of course read the fine print first (on a picture page, look for a link that says "some rights reserved" or similar), but in general I don't think you'd have any problems using it for a divisional website. Unfortunately searching for "fencing" gets you a lot of pictures of barbed wire and pickets. I had better luck using terms like epee, foil fencing, etc.