I travel there for business from time to time. Watertown itself has been mostly tapped from local CRH'ers. However, the locals don't tend to hunt the outskirts. Some of those areas (within 20 miles of Watertown) have goodies (especially halves). Try these towns:
Adams(South of Watertown)
Champion (East of Watertown)
West Carthage (Part of Champion)
Carthage (Part of Wilna)
Philadelphia (East of Watertown)
Lowville (East of Watertown)
You can get a list of banks for these places by using
http://www.yellowpages.com. KeyBank tends to be the most productive with coin.
Please let us know how it goes.