I think your crayfish is an immature due to the size of its front 'claws'. Try to get a couple pictures of one with larger front claws and a clear close pic of the head from the top view. I think your crays are one of the genus Orconectes. Maybe a 'northern crayfish' O.virilis?

aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management