Silent Valley movement was a social movement aimed at the protection of Silent Valley, an evergreen sub-tropical forest in the Palakkad district of Kerala, India. It was started in 1966 by an NGO led by Kerala Sasthra Sahithya Parishad (KSSP) to save the Silent Valley from being flooded by a hydroelectric project. In February 1973, the Planning Commission approved the project at a cost of about Rs. 25 crores. The valley was declared as Silent Valley National Park in 1985.