I found this pretty interesting:

http://whiskyadvocate.com/whisky/201...gs-raj-bhatka/

Especially this:

In any case, he is talking now, and is completely candid that the whiskey they are bottling today is still from the same single Canadian source, not five distilleries as Pickerell implies. “Yes, we’ve been growing our own grain,” he continued, “and we have been contracting others to distill it for us. We wanted to see how it turned out. That whiskey is currently maturing on the farm in Vermont, but it is not yet ready for release.” And the whiskey in the bottles? It’s still all Canadian rye whiskey, and will be for years to come.
So, which American distilleries are contract distilling 100 percent rye for WP?