Pashan Lake Crisis: Plant Overload Triggers Fish Deaths

An investigation into the Pashan Lake fish deaths has revealed that the local sewage treatment plant (STP) was severely inadequate for the volume of waste it received. The STP, designed for 1 million litres per day (MLD), was handling nearly 10 MLD of untreated sewage from Bavdhan and Bhugaon, far exceeding its capacity and critically degrading water quality. This situation was exacerbated by major flaws in the sewer network, where new lines were incorrectly connected to smaller pipelines, overwhelming the Pashan facility.

The report also highlighted technical issues within the STP, noting actual chemical oxygen demand (COD) levels as high as 722 mg/l, significantly above the design limit of 400 mg/l. These elevated levels likely hampered bacterial activity and treatment efficiency. While the plant operated between August 2025 and January 2026 and underwent maintenance in February 2026, its 'recycle mode' operation during inspection did not confirm a complete shutdown. No scientific investigation or water quality analysis was conducted to definitively link the STP to the fish deaths.

Environmental factors, such as the proliferation of water hyacinth and a subsequent drop in dissolved oxygen, are considered potential significant contributors to the fish mortality. Investigations into allegations of chemical discharge from HEMRL and Bharat Electronics Limited found no evidence. The findings emphasize a multi-dimensional cause for the incident, recommending the formation of an independent expert committee, removal of water hyacinth, correction of sewer connections, and development of standard operating procedures to prevent future occurrences.