Fencing of my property

I have one acre of Land in Kerala. I inherited it from my Grandfather. The Plot is a square shaped plot. On the Northern border is a Government Public road which is a state high way. On the southern border is a small stream and on the banks of stream is a colony of about 50 families of 4 cents each. The colony was given by the government under landless people rehabilitation scheme. Everybody has enough wells and also there is public well in the colony given by the govt. Inside my plot On the Northern border there was a small pond 1 meter square. About one meter away from the Northern border wall of the high way, And about 4 feet depth. It has water coming from a rock and people sometimes used to draw water during summer times as water is clean. They entered through the southern border and we never objected. It is a small pond with 3-4 Pots of water only. Now last year the High way was widened by one meter and the highways new wall should have come over the pond, filling up the pond. But the few families who use this Pond has complained to the contractor who widened the highway, who is a local politician also and he instead of filling up the pond, put a concrete block over the pond and conserved the pond. Now the pond stands under the wall of the highway. But the only way which the pond can be accessed is through my property. I was not in station and I came to know about this once I came back only, now I plan to fence four sides of the property. People will create problem telling that they cannot access the pond. Can I get legal protection for fencing off my property?. The Pond is not their primary source of water. They have many other sources and it is an additional source only.