Under the Clean Water Act (CWA), EPA establishes national technology-based regulations known as 'effluent guidelines and pretreatment standards' to reduce pollutant discharges from categories of industry discharging directly to waters of the United States or discharging indirectly through Publicly Owned Treatment Works (POTWs). The CWA sections 301(d), 304(b), 304(g), and 307(b) require EPA to annually review these effluent guidelines and pretreatment standards. This document supports EPA's 2005 review of its existing effluent guidelines and pretreatment standards. It also presents EPA's evaluation of categories of indirect dischargers without pretreatment standards to identify potential new categories for pretreatment standards, as required under CWA sections 304(g) and 307(b). Additionally, CWA section 304(m) requires EPA to biennially publish an effluent guidelines program plan and provide for public notice and comment on such plan. Therefore, this document also supports the preliminary 2006 effluent guidelines program plan ('2006 Plan'). Included in the preliminary 2006 plan is a solicitation for comments and data on industry categories currently not subject to any effluent guidelines that are discharging non-trivial amounts of toxic or non-conventional pollutants. EPA's annual review of effluent guidelines and pretreatment standards has several components. First, EPA reviews all industrial categories subject to existing effluent limitations guidelines and standards to identify potential candidates for revision, as required by the Clean Water Act sections 304(b), 301(d), 304(g) and 307(b). The findings of this review are discussed in section 7.0 of this report. Second, EPA reviews direct discharging industries not currently subject to effluent limitations guidelines to identify potential candidates for effluent limitations guidelines development, as required by section 304(m)(1)(B) of the Act. The findings of this review are discussed in section 5.4 of this
report. Finally, EPA reviews indirect discharging industries not currently subject to pretreatment standards to identify potential candidates for pretreatment standards development, as required by section 307(b). The findings of this review are discussed in section 5.4.2 of this report.