Negotiators disbanded on Friday without a plan for the basin supplying water to 40m people, thrusting the region into uncertainty

The future of the American west hung in the balance after seven states remained at a stalemate over who should bear the brunt of the enormous water cuts needed to pull the imperiled Colorado River back from the brink.

Negotiators, who have spent years trying to iron out thorny disagreements, ended their talks on Friday without a deal – one day before a critical deadline to form a plan that had been set for Saturday.