1. Short title This Act may be cited as the Primacy Certainty Act of 2023 . 2. State primary enforcement responsibility for Class VI wells (a) Amendments Section 1422(b) of the Safe Drinking Water Act ( 42 U.S.C. 300h–1(b) ) is amended— (1) in paragraph (2)— (A) by striking (2) Within ninety days and inserting the following: (2) Required timeline (A) In general Within 90 days ; and (B) by adding at the end the following: (B) Notice related to State primary enforcement responsibility for Class VI wells (i) Definition of Class VI well In this subparagraph, the term Class VI well has the meaning given the term in section 40306(a) of the Infrastructure Investment and Jobs Act ( 42 U.S.C. 300h–9(a) ). (ii) Notice to State If the Administrator does not approve, disapprove, or approve in part and disapprove in part the State's underground injection control program for Class VI wells by not later than 180 days after the date on which the application of the State is submitted under paragraph (1)(A) or notice of the State is submitted under paragraph (1)(B), the Administrator shall transmit to the State, in writing, a detailed explanation that describes— (I) the status of the review of the application or notice, as applicable; (II) the reason for which a decision with respect to that application or notice has not yet been made