Joe as has been said, in most cases pumping from a stream is not a great idea, but you might want to be prepared for a drought.
Check the stream for species of fish and determine if you want to use it as a back up plan to keep your pond from drying up.
The main supply of water for my pond comes from gravity siphon pipes from a stream, but the stream only contains trout, PS's, and crayfish which I already have in the pond, this is acceptable to me because without stream water I would have no pond.
