Noted human rights crusader Avdhash Kaushal has threatened to return the Padma Shri he had received for environment protection in 1986 if the Central and State governments do not immediately order resumption of construction work for the 480-MW Pala Maneri, 381-MW Bhairav Ghati and 600-MW Lohari Nagpala hydel projects in Uttarkashi district of Uttarakhand.