Manas River
The river valley has two major reserve forest areas , namely the Royal Manas National Park ( , established in 1966 ) in Bhutan and the contiguous Manas Wildlife Sanctuary ( in 1955 increased to in December 1985 ) encompassing Project Tiger reserve , an elephant reserve and a biosphere reserve , which constitutes a UNESCO World Heritage Site declared in December 1985 . 
<triplet> Royal Manas National Park <subj> 1966 <obj> inception <triplet> Manas Wildlife Sanctuary <subj> World Heritage Site <obj> heritage designation <triplet> World Heritage Site <subj> UNESCO <obj> maintained by