So there I was, gabbing happily with Pat Hayes of Hayes Family Farm on Saturday at the Boston Local Food Festival when he said proudly that Organic Valley, the largest organic dairy cooperative in the country, supplies all the milk to Stonyfield Farm for its organic yogurt.

Are you sure? I asked him. I could swear I heard Gary Hirshberg, CEO, tell a story at the Commonwealth Club about how the company had done a study in which sourcing dried milk from New Zealand, where organic farming is more widespread, is more environmentally sound than sourcing it from the US, where trucks would have to go from relatively isolated organic farm to organic farm, collecting relatively small amounts. And, I'd assumed from that that Stonyfield uses dried New Zealand milk in its products.

Yes, I'm pretty sure, Pat said.

So, I called Stonyfield. Here's what communications manager Sarah Badger told me: It's true that Stonyfield commissioned such a study, but never followed through to actually buy any. Organic Valley does indeed provide all Stonyfield's milk, mostly from New England and New York, because that makes the milk both organic and local, the sustainability double play.

She added that no one would reconstitute dried milk to make yogurt. She said Stonyfield adds dried milk as a texture builder, since it doesn't use guar gum or other such thickeners. She said its dried milk also comes from Organic Valley.

While I had her on the phone, I asked if Stonyfield would disclose if it made any private-label yogurt, and she said yes, but not for whom, as a provision of their contract. I'd heard, and Wikipedia also says, that the private label is Trader Joe's. There's also this "proof." I believe it.