In the sands of the Negev Desert, small groves of eucalyptus, olive and pomegranate trees grow in shallow depressions dug out to catch floodwater, a method used by the Nabateans thousands of years ago.

The ancient technique is one way Israelis are trying to harness every drop of water, an effort that has become critical as the country reels from its fourth straight year of drought. Experts say Israel is in the worst water crisis it has ever seen.

“We don’t have any water to waste,” says Elisha Mizrahi, director of the Jewish National Fund’s southern region, which initiated the project. He looks out onto the groves, the only hint of green for miles.

As Israel’s population swells, increasing water demands have exacerbated the effects of below-average rainfall rates.

The country’s three main reservoirs, including the Kinneret, have dropped below their emergency lines. If the water levels continue to sink, Israel may have to limit water use from the Kinneret in the wintertime. The government has cut back on water allocations for farmers and industry, and the Israeli public is being urged to reduce usage in an aggressive TV campaign featuring a woman whose face cracks up like a parched piece of earth.

Israel has made strides in using recycled sewage water for irrigating farmland. About 75 percent of all sewage water is treated and then used for agriculture, making Israel the world’s leading nation in the field. By contrast, the runner-up, Spain, recycles 12 percent of its wastewater.

“We are creating a source for irrigation that otherwise would not be used,” Avi Gafni, a JNF hydrologist and research coordinator, said while standing in front of one of the 200 reservoirs the JNF has built in Israel to store treated sewage water. “Every drop of water can make the land here potentially into agricultural land.”

The reservoirs make up about 16 percent of the total volume of Israel’s water reserves. About 30 percent of Israeli water used every year is recycled wastewater or desalinated water.

But the water savings aren’t enough in this parched land. Compounding the water crisis is the country’s reliance on ground water, which provides about two-thirds of Israel’s drinking water.

“With the depletion of the water table from the ground there are opportunities for saltier water to seep in and contaminate the fresh water,” said Avner Adin, founder of the Israel Water Association and a professor at Hebrew University’s Department of Soil and Water Sciences.

“These are very difficult processes to reverse,” Adin said. The water shortage might become “a catastrophic situation if not handled properly,” he warned.

Some water experts say the current crisis could have been averted had Israel followed through on its plans after the last water crisis, several years ago, to build new desalinization plants. The Israeli government approved their construction as far back as 2002, but the rate of building slowed when Israel experienced several years of above-average rainfall and investors, including the government, delayed construction of the plants.

Israel has two desalinization plants, and a third one is about a year away from completion. But the country’s desalinization capacity is just one-third of what it was supposed to be according to the government’s plans.

Last month the Knesset established a commission of inquiry to determine why the government’s desalinization recommendations were not implemented.

“This is not a water crisis; it’s a political crisis,” said Arnon Soffer, a geography professor at Haifa University.

Uri Schor, spokesman for Israel’s Water Authority, the government agency responsible for water issues, says expanding desalinization capacity “is a process.”

The desalinization plant in Ashkelon is the largest of its kind in the world, he noted, and by 2020 Israel will have built enough plants to desalinate 750 million cubic meters of sea water per year.

“This will stabilize the water situation in the medium- and long-term,” Schor said.

In addition to the desalinization plants, Schor said Israel’s strategy to tackle the water problem is to continue its pioneering work in recycling sewage water for agriculture.

In the short term, however, the plan is to reduce usage by cutting agricultural and industrial allocations, raising household consumer water prices and running public awareness campaigns. The higher water prices also will help pay for the desalinization plants and the extensive new pipeline networks they will require.

Booky Oren, president and CEO of Miya, a $100 million company that invests in water technology, says Israel must harness its talents in water management.

“The difference about today is that there are the technological tools to cope with this crisis,” said Oren, a former director of Israel’s national water company, Mekorot, who touts Israel as the Silicon Valley of water technology. “When people take responsibility and don’t wait for rainfall alone, we can assist nature and help find solutions.”