AIADMK general secretary Jayalalithaa on Monday urged Chief Minister M. Karunanidhi to take steps to prevent the Andhra Pradesh government from going ahead with its plans to construct 10 checkdams across the Ponnaiyaru. In a statement here Ms Jayalalithaa said the Ponnaiyaru was the source of drinking water for Vellore, Kancheepuram, Thiruvallur and Thiruvannamalai districts and construction of check dams would deprive these districts of their drinking water supply. The Ponnaiyaru originates in Srisailam in Andhra Pradesh and confluences with the Palar in Thiruvalam near Vellore.