Ensuring that an acceptable level of electric system reliability is maintained as the Clean Power Plan is implemented is in everyone’s interest. This short paper suggests ways states can think about their reliability targets and associated tolerance bands in assessing whether possible compliance plans will maintain a level of system reliability that is consistent with established consumer expectations. In the unlikely event that a state explores the full range of flexibility options available from the variety of carbon reduction tools at its disposal, and determines that its reliability standard cannot be met within reasonable tolerance limits, then consideration of a safety valve option may be appropriate. The safety valve offered by EPA under such circumstances should be a temporary deferral that ensures a return to compliance in a timely fashion.