In this action, we are adopting emission standards for new marine diesel engines installed on vessels flagged or registered in the United States with displacement at or above 30 liters per cylinder. These standards are equivalent to the internationally negotiated standards for oxides of nitrogen and will be enforceable under U.S. law for new engines built on or after January 1, 2004. The certification and compliance program we are adopting is similar to the internationally negotiated program, but contains additional provisions reflecting certain Clean Air Act-specific compliance provisions and the related need to adopt test procedures designed to achieve the emission reductions called for under Clean Air Act section 213. These standards will apply until we adopt a second tier of standards in a future rulemaking. In developing that future rulemaking, which will be completed no later than April 27, 2007, we will consider the state of technology that may permit deeper emission reductions and the status of international action for more stringent standards. We will also consider the application of such a second tier of standards to engines on foreign vessels that enter U.S. ports. We are also adopting additional standards for new engines with displacement at or above 2.5 liters per cylinder but less than 30 liters per cylinder. These standards, which are currently voluntary, are also equivalent to the internationally negotiated standards for oxides of nitrogen. The standards will apply through 2006. Beginning in 2007, the Tier 2 standards we finalized for these engines in 1999 will go into effect (64 FR 73300, December 29, 1999; 40 CFR part 94).