The May 31, 2011 Federal Register announced that effective April 11, 2011, EPA Region 1 has signed an agreement with the Massachusetts DEP (MassDEP) delegating authority to implement and enforce the Federal Prevention of Significant Deterioration (PSD) program to the MassDEP. Therefore, the MassDEP is now the implementing authority for the PSD program in Massachusetts. The Federal Register notice can be found here