We are approving a revision to the Minnesota State Implementation Plan (SIP) which updates Minnesota's performance test rule in the SIP. The Minnesota Pollution Control Agency (MPCA) submitted the proposed revision to EPA on December 16, 1998. The proposed revisions set out the procedures for facilities that are required to conduct performance tests to demonstrate compliance with their emission limits and/or operating requirements. The request is approvable because it satisfies the requirements of the Clean Air Act (Act). The rationale for the approval and other information are provided in this notice.