The link at the end of the post says that Indian Black Turtle or Indian Pond Terrapin (Melanochelys trijuga) is limited to the northern low wet and dry zone parts in Sri Lanka, but I've seen them often in the western province too, where there is still or slow flowing fresh water such as rice fields, ponds, rain-filled old granite mines etc.
Image by roosterfeather via FlickrIt's said that these tortoises are near threatened. One factor which may contribute to that in Sri Lanka is that people have a taste for it's meat. Some people hunt these and some times these critters bite on fishing bait get themselves caught.
Image by roosterfeather via Flickr
This link here provides a whole lot more information on Indian Black Turtle.
PS-Hi all, Looks like my identification of this animal is not entirely correct,as my friend Bushana says in his comment. I'll quote him here in case you don't notice it.
"............What you have photographed here is Spotted black turtle(Melanochelys trijuga thermalis) a sub species with a face with bright red, orange or yellow spots. This subspecies has wide distribution in Sri Lanka(It doesnot imply that it is common) and specimens were reported from varies places throughout the country such as Colombo, Jaffna, Trinco, Kandy,Anuradhapura, Tissamaharama, Kalpitiya, Welimada..etc. Other subspecies M.t.parkeri or Parker's Black turtle -comparatively larger than this one and no color spots on the face- is restricted to Northern part of the country. So as a species it is distributed throughout whole island in suitable habitats contrary to what it is said in the link you have given above............"