On which river was the Sardar Sarovar Dam being built, which met with widespread protests?

Narmada

An ambitious developmental project was launched in the Narmada valley of central India in early eighties. The project consisted of 30 big dams, 135 medium sized and around 3,000 small dams to be constructed on the Narmada and its tributaries that flow across three states of Madhya Pradesh, Gujarat and Maharashtra. Sardar Sarovar Project in Gujarat and the Narmada Sagar Project in Madhya Pradesh were two of the most important and biggest, multi-purpose dams planned under the project Narmada Bachao Aandolan, a movement to save Naramada, opposed the construction of these dams and questioned the nature of ongoing developmental projects in the country.