EPA is taking direct final action to simplify an existing provision in our marine diesel engine program that is intended to encourage owners of Great Lakes steamships to repower those steamships with cleaner marine diesel engines. The simplified program will automatically permit the use of residual fuel, through December 31, 2025, in a steamship if it has been repowered with a certified Tier 2 or later marine diesel engine, provided the steamship was operated exclusively on the Great Lakes and was in service on October 30, 2009. Steamships are powered by old, inefficient steam boilers. Voluntary replacement of these boilers with modern fuel-efficient marine diesel engines will result in reductions of particulate matter and sulfur oxides, even while the replacement diesel engines are operated on higher sulfur residual fuel, and will provide human health and welfare benefits for the people who live in the Great Lakes region. Conversion to new diesel engines will also result in considerable carbon dioxide reductions and fuel savings.