Bagmati

The Bagmati rises at Bagdwar — the 'tiger's mouth' spring at about 2,740 m in the Shivapuri hills of what is now Shivapuri Nagarjun National Park — and flows down through the Kathmandu Valley, separating the old royal cities of Kathmandu and Patan and gathering the Bishnumati, Manohara and Nakkhu along the way. It then cuts south through the Mahabharat range to the Madhesh plains and on into Bihar, where its waters eventually reach the Koshi.

No Nepali river carries more religious weight per cubic metre. At Pashupatinath — the great temple of Shiva on its banks, part of the Kathmandu Valley UNESCO World Heritage Site inscribed in 1979 — Hindus are cremated at the riverside ghats, the dead traditionally dipped three times in the Bagmati before the pyre is lit. For the valley's civilisation, Newar and Hindu alike, the Bagmati is the axis of ritual life from birth to death.

That sanctity collides with the valley's sewage. Through Kathmandu the river receives large volumes of untreated waste — the Bishnumati tributary is the most degraded — and restoring it has become a civic cause: the Bagmati Mega Clean-Up Campaign, launched in 2013, has mobilised volunteers, officials and soldiers every Saturday for years, alongside donor-funded basin-improvement works.

Hydrologically the Bagmati is a Mahabharat-origin river — fed by springs and monsoon rain rather than glaciers, so its flow swings sharply between seasons. Its Kulekhani tributary, impounded by a 114 m dam to form the Indra Sarovar reservoir, feeds the Kulekhani I, II and III stations (60 + 32 + 14 = 106 MW) — Nepal's only seasonal-storage hydropower, the battery the grid leans on in the dry months. Downstream, the Bagmati Irrigation System waters the central Tarai, soon to be augmented by Sun Koshi water via the Sunkoshi–Marin tunnel.