40 CFR §51.212

1. (a)Periodic testing and inspection of stationary sources; and
2. (b)Establishment of a system for detecting violations of any rules and regulations through the enforcement of appropriate visible emission limitations and for investigating complaints.
3. (c)Enforceable test methods for each emission limit specified in the plan. For the purpose of submitting compliance certifications or establishing whether or not a person has violated or is in violation of any standard in this part, the plan must not preclude the use, including the exclusive use, of any credible evidence or information, relevant to whether a source would have been in compliance with applicable requirements if the appropriate performance or compliance test or procedure had been performed. As an enforceable method, States may use:
   1. (1)Any of the appropriate methods in appendix M to this part, Recommended Test Methods for State Implementation Plans; or
   2. (2)An alternative method following review and approval of that method by the Administrator; or
   3. (3)Any appropriate method in appendix A to 40 CFR part 60.