Prime minister Narendra Modi inaugurated India's biggest dam on Sunday, ignoring warnings from environment groups that hundreds of thousands of people will lose their livelihoods. The controversial Sardar Sarovar Dam on the Narmada river in the country's western state of Gujarat will provide power and water to three big states. Mr Modi dedicated it to the people of India. The project has been beset by controversies since the laying of the foundation stone by prime minister Jawaharlal Nehru in 1961. The construction of the project began in 1987. The dam is the second biggest in the world after the Grand Coulee Dam in the United States. Ahead of the inauguration Mr Modi tweeted, "This project will benefit lakhs (hundreds of thousands) of farmers and help fulfil people's aspirations". The dam is expected to provide water to 9,000 villages and the power generated from the dam will be shared among three states — Madhya Pradesh, Maharashtra and Gujarat. But the Narmada Bachao Andolan (NBA) activist group has been protesting against the project, raising several environmental concerns. Construction on the dam was suspended in 1996 following a stay by the Supreme Court. The court allowed work to resume four years later, but with conditions. NBA leader Medha Patkar and her supporters began on Saturday their protest against the inauguration of the dam and the opening of its gates which will raise the level of water and risk displacing several villages. "Today is a very sad day for India, and for one of our biggest peoples' movements and struggle — the Narmada Bacchao Andolan," said Ravi Chellam, executive director at Greenpeace India. "The Sardar Sarovar Project … signals ruin not development for tens of thousands of unsuspecting, hapless and poor farmers."