In 1981 Prof.C.V.Subramanian, the internationally acclaimed mycologist, wrote to Mrs Indira Gandhi, seeking her intervention to stop the Dam construction which held very unique flora and fauna. Prof Subramanian also submitted a report on the Silent Valley on the basis of which Mrs Gandhi, decided to abandon the project. The Silent Valley forests were declared as a National Park. On 7 September 1985 the Silent Valley National Park was formally inaugurated and a memorial at Sairandhri to Indira Gandhi was unveiled by Rajiv Gandhi, her son and the next Prime Minister. On 1 September 1986 Silent Valley National Park was designated as the core area of the Nilgiri Biosphere Reserve. Since then, a long-term conservation effort has been undertaken to preserve the Silent Valley ecosystem.