The Environmental Protection Agency (EPA) is proposing to approve a revision to the Wisconsin state implementation plan (SIP), submitted by the Wisconsin Department of Natural Resources (WDNR) on September 30, 2008. The revision updates the definition of ``Replacement Unit'' and clarifies a component of the emission calculation used to determine emissions under a plantwide applicability limitation (PAL) in the Wisconsin Administrative Code. Approving this revision makes Wisconsin rules consistent with Federal rules.