Carrick-on-Shannon's 30-million-euro flood-defence scheme will go to planning in 2026.
The project has been worked on for several years, after the town was badly affected by flooding in 2009 and 2015.
It will involve embankments and other flood-defence systems along the Shannon.
Leitrim County Council chief executive, Joseph Gilhooly, says it will go to planning in the first half of 2026 and be finished around five years later.