COIMBATORE: Tension flared at Nagammanayakkanpalayam in Sulur assembly constituency on Friday after residents opposed a plan to desilt a 70acre pond and fill it with treated sewage water from the city, leading to a protest during which stones were allegedly thrown at Sulur MLA N M Sukumar.The project involved desilting the pond and subsequently releasing treated wastewater into it. Residents said the pond plays a key role in recharging nearby wells and borewells during the monsoon and supports agriculture on several hundred acres of land. They alleged that letting treated sewage into the waterbody could alter water quality and render it unsuitable for continued use, insisting the pond should store only rainwater.When the MLA arrived to inaugurate the desilting work, villagers reportedly surrounded him and staged a protest. Despite the opposition, a bhoomi puja for the work was performed in the presence of party cadres, following which an argument broke out between residents and those present. Police said some protesters allegedly hurled stones. But stones didn’t hit the MLA.Security was stepped up with additional police deployment. Police resorted to a mild lathicharge to disperse the crowd, officials said. Protesters later blocked an earthmover brought to the site for the desilting operation. Talks were held subsequently. Police said an inquiry was under way into the stone-throwing incident.Sukumar alleged that over the last five years, DMK had not carried out development work in the constituency and that groundwater levels had fallen sharply, necessitating such interventions. He said consultation had been held with local people about the project. He accused a DMK functionary of spreading false information among the public about it.