Actually, the Russian textile industry needed cotton, they were a major customer of US cotton, then they saw an opportunity to grow cotton in Turkestan. So they started growing cotton there. Even after the 1917 revolution, Turkestan remained a major cotton producer, and population growth, increasing demand for cotton, the ruthless Soviet central planning dried the lake. That YouTube clip might have a point about water leaks, but even with 100% efficiency they would dry up the lake anyway, the inertia to grow cotton was too strong.