Israel and Jordan have relaunched the £500m "Red-Dead" project - the plan to construct a canal between the Red Sea and the Dead Sea.
The two countries, which made peace 21 years ago, have both insisted on the environmental importance of the project. Jordan's King Abdullah and Israeli Interior Minister Silvan Shalom both declared at this week's climate conference in Paris that it would "save the Dead Sea".
The Dead Sea is shrinking, and there is heavy international pressure on both sides to stop its demise.
The new "Red-Dead" project - which is more modest than "Red-Dead" initiatives discussed in recent years - will boost Jordan's desalination capabilities, allowing it to sell water on to Israel.
This water will be used in Israel's dry southern district, while in the country's north, where there is better water provision, Israel will increase water supplies from the Sea of Galilee to Jordan.
The salty brine that is produced in the desalination process will then be used to top up the Dead Sea.
But while Mr Shalom said that moving forward the project was "an extraordinary environmental and political achievement", some environmental groups have their doubts.
Gidon Bromberg, director of the Israeli branch of EcoPeace Middle East, said that while he welcomed the water-exchange mechanism, the plan "doesn't really reverse anything" in terms of the Dead Sea.
Mr Bromberg said that the brine would only very slightly slow the shrinkage of the Dead Sea, adding that he worries about the ecological impact of introducing desalination brine into the naturally formed water basin. He said that rather than actually helping the Dead Sea, the project just "gives the impression still that we're doing something".