With a call to put an end to the exploitation of ground water in the ecologically sensitive Nilgiris district, World Water Day was observed under the aegis of the Public Awareness Association of Udhagamandalam here on Thursday. A signature campaign marked the occasion. Participants pointed out that the sinking of bore wells which was until a few years ago unheard of in Udhagamandalam and many other parts of the district is of late on the rise.