After following the Ganga from Gangotri, through Uttar Pradesh, the NDTV and TERI team arrives in Bihar. Even here, our tests revealed high levels of bacteria contamination in the water, but it was also home to the endangered Gangetic river dolphin which gave us hope. The river then crosses to Bengal as the Hooghly, where once again household waste and industrial effluents are dumped into her waters. And before she enters the Bay of Bengal, her final gift, the Sundarbans, the world's largest mangrove forests.