Blocked drains lead to flooding in South Bengaluru; Bellandur lake overflow raises alarm

Heavy rainfall in Bengaluru has once again exposed the poor drainage infrastructure in the Bommanahalli and Silk Board regions, resulting in severe waterlogging and local flooding. The release of excess stormwater into Bellandur Lake has triggered public and political concern.

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Stormwater from approximately seven surrounding localities, including Meenakshi Temple, Arekere, Bilekahalli, and Madiwala is being diverted into Bellandur Lake. This includes runoff from areas as far as BTM Layout and Koramangala. The water reaches the lake through two main stormwater drains (rajakaluves), each 60 feet wide. However, officials have only allowed a 30-foot outlet at the entry to Bellandur Lake. The rest of the space has been blocked with soil and stones, restricting the natural flow.

Heavy rainfall measuring 103 mm lashed Bengaluru city on Sunday midnight, leading to widespread waterlogging and urban flooding. The Bellandur Lake diversion channel and the KC Valley were completely choked, resulting in severe inundation across key areas including BTM Layout,… pic.twitter.com/iitvNZMYl3

— Karnataka Portfolio (@karnatakaportf) May 19, 2025

During heavy rains, this partial blockage causes water to overflow into residential areas, creating artificial flooding. Authorities had previously closed this outlet to prevent sewage and untreated water from entering the lake, following National Green Tribunal (NGT) guidelines. While the intention was to stop sanitary water from polluting the lake, no alternative route for stormwater was provided.

Transport Minister Ramalinga Reddy visited the Bellandur Lake site to inspect the situation. He emphasized the urgent need to construct a functional gate that would allow only rainwater to pass into the lake while blocking sewage. He also stated that he plans to take the Chief Minister and Deputy Chief Minister to the site to explain the gravity of the situation.

The lack of proper water flow channels has led to flooding in low-lying areas like Koramangala, intensifying the call for immediate corrective action.