Low Enroute IFR charts in Alaska (and maybe elsewhere?) have blue routes and MEAs for GPS equipped aircraft, such as T266, 7000G MEA, below. Is an IFR GPS sufficient to use these, or is WAAS required?

Low Enroute IFR charts in Alaska (and maybe elsewhere?) have blue routes and MEAs for GPS equipped aircraft, such as T266, 7000G MEA, below. Is an IFR GPS sufficient to use these, or is WAAS required?

The answer appears to be yes. The FAA document that describes this rule says:
TSO C145a and TSO C146a GPS WAAS navigation systems are authorized to be used as the only means of navigation on Federal airways and other published ATS routes in lieu of ground-based navigation aids in Alaska
The IFR chart legend says:
To utilize these routes aircraft will need to be equipped with IFR approved Global Navigation Satellite System (GNSS). In Alaska, TSO-145a and 146a equipment is required.
And both TSO C145 and C146 specifically mention WAAS in their titles.