Work on the much-delayed 3,600-MW Soviet-era Rogun hydro dam in Tajikistan is resuming under a $3.5-billion deal with Milan-based Italian contractor Salini Impregilo S.p.A. Destined to be the world’s tallest dam, the 335-meter-tall earthfill structure will obstruct flows in the Vakhsh River, raising opposition in the cotton-growing downstream state of Uzbekistan.

Salini Impregilo this July secured a 13-year framework agreement with the Tajik state’s utility OJSC Rogun HPP to complete the project, which lies about 110 kilometers east of the capital Dushanbe, in phases. The company says it has secured a firm $1.75- billion deal to finish the dam and get two of its six 600-MW turbine units operational by August and October 2018, respectively.