Did you know they have an 'app' for that!
That's right, an app to help you find non E-10 (or E-15) gas.
Please note that I just found this the other day and haven't used it yet, other than to check to see what it shows in our area.
The app is called "Pure Gas" and I have it on my Android, I understand there may be an Apple version too. It's supposed to be driven by the pure-gas.org website.
Note that the app lists Channel Marine as having 'Ethanol-free VALVTECT 89 and 91 Octane'. I have not tried to verify this information. The info may be entered by end users, so I suppose that it could be incorrect, but I hear everything on the Internet is true. How do I know? They said so on the Internet!