Ein Gedi , Israel -- The Dead Sea covers about 250 square miles in a deep valley bordered by Israel, Jordan and the West Bank. But to understand why the sea is dying, begin about 60 miles north, at a spot just below the Sea of Galilee that today is the northernmost source of water for the lower Jordan River -- an open drain that pumps out 720,000 gallons of raw sewage a day.

White foam flutters in small pools around rocks. Chunks of concrete, strips of plastic piping, bicycle tires and other litter clutter the shore. The stench of human waste fills the air. If the scene is not cautionary enough, a sign warns: "Danger! Don't enter or drink the water."

"This is the end of the Jordan River as far as clean water is concerned," Gidon Bromberg, head of the Tel Aviv office of Friends of the Earth Middle East, said as he walked around the site. "From here down to the Dead Sea, the Jordan River has been turned into a sewage canal -- little more."

The Jordan -- best known as the river where Christians believe Jesus was baptized -- used to be the main source of water for the Dead Sea, delivering about 1.3 billion cubic meters of water every year, or about three- quarters of all the water that flowed into the sea.

Today, virtually every major spring and tributary that once flowed into the Jordan has been dammed or diverted for drinking water and crop irrigation by Israel, Jordan, Lebanon and Syria. The Jordan now delivers less than 100 million cubic meters of water a year to the Dead Sea, and as much as half of that is raw sewage, according to Bromberg and other environmentalists.

Months go by in the summer when parts of the river are dry. At Jesus' baptismal site, five miles north of where the Jordan trickles into the Dead Sea, pilgrims fill souvenir bottles with greenish-brown water.

"The irony is that today the Jordan is being kept alive by sewage," Bromberg said.

As the level of the Dead Sea falls, it affects everything around it. Underground pools of fresh water are retreating, pulling water away from plants in major wildlife areas bordering the Dead Sea. The fresh water is hitting pockets of salt deep underground and dissolving it, causing the earth above to collapse into giant sinkholes, which recently forced the closure of an army camp and a trailer park. As the shoreline shifts, rain runoff digs deep gorges in the newly exposed landscape and wipes out roads and any other infrastructure in its path.

"The real solution is that we need to be smarter and use our water in a wiser way," said Ariella Gotlieb, a biologist with Israel's parks authority who works at the Ein Gedi Nature Reserve, an oasis of dense tropical plants, hyenas, ibex, wolves and more than 200 species of birds. The reserve is one of several plant and wildlife sanctuaries threatened by changes in the local ecosystem.

Gotlieb and others said the traditional Zionist dream to "make the desert bloom" has to be updated to reflect the scarcity of resources in a more densely populated country. She pointed to the reserve's neighbor, Kibbutz Ein Gedi, and said it was no longer appropriate for residents there to use natural spring water to tend fruit groves and a botanical garden with more than 800 species of exotic plants in the middle of the desert. Of the 3 million cubic meters of water that flow from Ein Gedi's four springs, not a drop reaches the Dead Sea anymore, she said.

"The Dead Sea is receding because the Jordan River is dead -- it has no relation to the botanical gardens," responded Meir Ron, a founder of the 550- resident kibbutz. He said the problem was a classic battle between man and nature.

"When I was born in Haifa in 1935, there were 600,000 people in Israel, and now there are more than 6 million," he said. "What can we do?"

From Masada, the mountaintop citadel that was fortified by Herod the Great and became a Jewish cultural icon and a symbol of the struggles of modern Israel, the view is of mud flats stretching for miles into Jordan.

"Herod built Masada overlooking the Dead Sea, but he'd turn in his grave if he could see what we've done to it," said Bromberg, the Friends of the Earth environmentalist. "You don't have to be Jesus to walk across the Dead Sea anymore."

Below Masada, the southern edge of the sea is about 15 miles north of where it used to be. From here, pumps siphon water into a six-mile canal that carries it through the mud flats to a large complex of evaporation ponds. Though marketed by Israeli hotels as the "southern basin" of the Dead Sea, the area is operated entirely by the Dead Sea Works chemical company to harvest minerals from the water. Without the pumps, the basin would soon go dry.

The evaporation process leaves a seven-inch residue of salt that settles to the bottom of the main pond every year, creating the exact opposite problem that the northern Dead Sea is facing. As the bottom rises, the water level does too, and posh Israeli hotels along the shore are building huge sand dikes in a losing fight against the floodwater.

The Sheraton hotel has had to rebuild and raise its dike three times to hold back the adjacent pond, which is now well above the hotel's swimming pool and ground floor, according to Udi Sicherman, chairman of the Dead Sea Hotel Association. The solution, he said, is a $200 million proposal to build a huge wall inside the ponds, creating a massive lagoon in front of the hotels where the water level could be controlled.

The Dead Sea Works, one of the world's leading producers of potash for fertilizer, operates an 18-mile-long maze of evaporation ponds. Discolored water that threatens to flood roads is held back by a network of dirt berms. The company's plant is a massive industrial complex surrounded by vast ponds and mountains of chemicals.

Environmentalists say that the Dead Sea Works evaporation ponds are responsible for 25 to 30 percent of the annual drop in the Dead Sea and that the company, which just had its state concession extended to 2030, is reaping a financial bonanza from the increased concentration of minerals in the water. "They are the only ones making good money. They want the water to decline," said Galit Cohen, head of environmental policy at Israel's Environmental Ministry.

Menachem Zinn, chief operating officer for Dead Sea Works, said the main cause of the sea's shrinkage was diversion of water from the Jordan River and other sources, not the company's evaporation ponds. He said the Dead Sea Works and industries that serve it employ about 35,000 people. The company recently completed a $70 million project to upgrade its ecological standards, he said.

"We try to keep the environment the best we can and at the same time make 3.5 million tons of potash and give so many families the ability to live from it," he said. At the Ein Gedi Spa, where manager Boaz Ron is watching the Dead Sea and his business dry up together, the answer is simple.

"You have to put a limit on things. If you can't put the water in, you have to stop taking it out," he said. "You need to reach a balance with nature, or the Dead Sea will become the Dry Sea."