Shifting rivers in India’s largest tea producing state and abnormally high rainfall this year is destroying hundreds of acres of tea gardens and could cut output in the world’s second-largest tea grower.

More than a tenth of the 18,000 hectares of plantations, or tea gardens, in India’s northeast state of Assam could be washed away as the mighty Himalaya-born Brahmaputra and other smaller rivers flood the region where century-old operations grow over half of India’s tea.

“Some tea gardens have already fallen into rivers and some of them are on the verge of disappearing,” said Dipanjol Deka, secretary general of Tea Association of India (TAI) in Guwahati, the main city in the region.