India, Sept. 18 -- The Kishau Multipurpose Project has finally crossed its most formidable hurdle: Six states-Himachal Pradesh, Uttarakhand, Haryana, Uttar Pradesh, Rajasthan and Delhi-have agreed to move ahead with a project that has travelled an extraordinary eight-decade journey from blueprint to breakthrough.

Conceived in 1940, Kishau has survived geological faults, shifting dam designs, repeated changes of site and prolonged bureaucratic and financial deadlock. Now, as the proposed dam rises from the drawing board on the Tons, a major tributary of the Yamuna, it carries ambitions far greater than hydropower. It is being presented as a regional water-security lifeline-linking irrigation, drinking and industrial water, power generatio...