The Prime Minister who arrived in the state on Saturday night, took the blessings of his mother Heeraba Modi near state capital Gandhinagar and went straight to the Narmada dam site in Kevadia.
The height of the dam has been raised to 138.68 metres.
The inauguration was attended by Chief Minister Vijay Rupani, Bharatiya Janata Party President Amit Shah, Union Minister Nitin Gadkari and several other religious and spirittual heads from the state.
Modi, earlier inspected the progress of work on the 182-metre Statue of Unity in memory of Sardar Vallabhbhai Patel being constructed at Sadhu Bet near the dam site.
He is expected to address a public rally at Daboi, and welcome the participants of the 10-day state-wide Narmada Yatra taken out in 85 chariots.
The Yatra will conclude on Sunday.