The construction of Chennai’s proposed sixth drinking water source, the Mamallan reservoir, has been temporarily halted. The Water Resources Department (WRD) stated that the pause is to review the project design and due to recent rainfall at the Vada Nemmeli site.
Despite the halt, the project has not been abandoned. Work will resume once a high-level committee provides its report and recommendations. This committee was formed to address concerns such as flooding risks and the impact on local fishermen’s livelihoods. Internal disagreements over design plans from different WRD divisions have also contributed to the delay.
Anna University has been asked to validate the designs and assess coastal impacts. The foundation for this ₹342.60 crore project was laid in January 2026, aiming to create a reservoir covering 5,161.27 acres with an annual storage capacity of 1.65 thousand million cubic feet. However, the project has faced opposition due to concerns about biodiversity loss, fishing communities, and coastal wetland damage.
About 10% of the work is complete so far. According to the WRD’s policy note for 2026-27, the reservoir will store 1.65 tmcft of water for drinking while releasing the remaining water into nearby estuaries to maintain ecological balance.