Change UTC settings Network-wide

I realize that the Blogs Template can help me out with this on a go-forward basis, but for the 1000 blogs already on my Multisite, is there a way to correct the UTC settings on every blog on the network. I know that all my bloggers live in the same timezone (it's a School Board Blogging platform) and want the General settings to reflect that to fix some glitches I'm seeing in the Buddypress activity stream.

I'm hoping for some way to perhaps set this in wp-config.php