India, April 21 -- On April 23 and 29, West Bengal will head to the hustings, to elect a new state assembly. This is certainly a purely domestic affair. Yet, across the border, in Bangladesh, the contest is sure to be followed closely. Dhaka's interest has nothing to do with political preference and is more about the consequences of the verdict - for Bangladesh, West Bengal is a geopolitical hinge, where domestic politics intersects with transboundary rivers, migration narratives, and the mechanics of bilateral cooperation.

The most immediate concern is water. The Teesta river is widely regarded as a "lifeline" for Bangladesh's northern districts - the mainstay of nearly 7.3% of Bangladesh's population. Efforts to reach a water-sharing a...