Pella Bird'n Lite upland vest or strap vest. I've got the upland vest and love it.
Can get a bit warm, but wore it this weekend hunting pheasants with a light long sleeve shirt. Was in the low 80's and not a big problem. Has pockets for water on each side. One for you and one for the dog.
http://www.ruggedclothing.com/pella-products/probably other places to get them.
