A plan to link the Red Sea with the shrinking Dead Sea could save it from total evaporation and bring desalinated water to thirsty neighbours Israel, Jordan and the Palestinians.
But environmentalists warn that the "Red-Dead" project could have dire consequences, altering the unique chemistry of the landmark inland lake at the lowest point on earth.
Jordanian Prime Minister Abdullah Nsur said on Monday that his government had decided to press ahead with the 980-million dollar project which would give the parched Hashemite kingdom 100 million cubic metres (3.5 billion cubic feet) of water a year.
"The government has approved the project after years of technical, political, economic and geological studies," Nsur told a news conference.
Under the plan, Jordan will draw water from the Gulf of Aqaba at the northern end of the Red Sea to the nearby Risheh Height, where a desalination plant is to be built to treat water.
"The desalinated water will go south to (the Jordanian town of) Aqaba, while salt water will be pumped to the Dead Sea," Nsur said.
The Dead Sea, the world's saltiest body of water, is on course to dry out by 2050.
It started shrinking in the 1960s when Israel, Jordan and Syria began to divert water from the Jordan River, the Dead Sea's main tributary.
Israel and Jordan's use of evaporation ponds for extracting valuable minerals from its briny waters has only exacerbated the problem.
With a coastline shared by Israel, the Palestinian Authority and Jordan, the Dead Sea's surface level has been dropping at a rate of around a metre a year. According to the latest available data form Israel's hydrological service, on July 1, it stood at 427.13 metres (about 1,400 feet) below sea level, nearly 27 metres lower than in 1977.
Under the plan most of the desalinated water would go to Jordan, with smaller quantities transferred to Israel and the Palestinian Authority.
But Friends of the Earth Middle East (FoEME) and other environmental groups have called on the three partners to reject it on environmental grounds.
The main concern, they say, is that a large influx of water from the Red Sea could radically change the Dead Sea's fragile ecosystem, forming gypsum crystals, and introducing red algae blooms.
In addition, leakage from the pipeline could contaminate groundwater along its route through southern Israel's Arava Valley.
The Israeli ministry of environmental protection says that studies so far leave "vast uncertainty" and it is calling for a pilot project to be run on a limited scale to study the potential implications.
But critics contend that a small-scale pilot might not carry enough water to trigger the effects that it is intended to examine.
And for the Palestinians, the joint project raises more basic political issues such as Israel allowing them to develop that part of the shore which lies within the Israeli-occupied West Bank.
"We would like to be in this cooperative project," says Shaddad Al-Attili, head of the Palestinian Water Authority. "We would like to be treated equally as well as the Jordanians and the Israelis, we would like to benefit from the outcome.
"But before all of that we would like to get access to the Dead Sea, not only to get water and to swim in the sea, but also to build hotels and to develop a tourist area."
The Dead Sea's mineral-rich waters and mud are considered therapeutic, while visitors love the novelty of floating in the brine which does not allow a person to sink. Israelis operate a number of tourist hotels and beaches along the western shoreline.
FoEME has called on the three partners to endorse a set of integrated actions including water recycling and conservation, rehabilitation of the lower Jordan River and even importing water from Turkey—one of three alternatives in a World Bank study that is estimated to be cheaper and have much less environmental impact than the Red-Dead option.
Prime Minister Nsur said Jordan wanted water to supply its northern regions, while Israel needs water in the south.
Jordanian officials say the 500,000 Syrian refugees that Jordan is hosting are stretching its meagre water resources.
The majority of refugees are living in the north, particularly the Zaatari camp, home to about 130,000 Syrians.
Jordan had initially agreed in principle to build, along with the Palestinians and Israelis, a $11-billion pipeline from the Red Sea to resolve the problem.
But Water Minister Hazem Nasser said that due to the high cost of that project Jordan had decided to opt for its alternative plan, "which we call the 'first phase'."
Jordan signed a peace treaty with Israel in 1994.
Explore further: Obama says 'no greater threat to planet than climate change'