Seawater intrusion is one of the critical issues in Tamil Nadu, and control measures must be taken to mitigate it. The Palar River is an important source of drinking water, especially for the atomic power plant located along the coast of the Bay of Bengal. Due to excessive ground water extraction, saltwater intrusion is observed. To address this problem, a dyke cum weir was proposed at Voyalur (12°28′52.12″N, 80°7′36.88″E) located 55 km east of Kanchipuram district and 64 km from Chennai district. The river stretch receives nearly 1100 mm of annual rainfall which is higher compared to the upstream reaches that receives lesser amount. Before the design phase, hydrometeorological analyses were conducted for the study area, specifically at five stations. A detailed soil investigation was made, and it reveals that a silt layer is present up to 8 m deep below the ground level. Based on the geotechnical analyses, a dyke cum weir type of check dam was proposed and completed by September 2019. The details of analyses and design benefits are detailed in the paper.