Libya's fragile government, grappling with marauding militias that have virtually shut down the country's vital oil industry, has another big problem in its struggle to impose control -- water supplies.

Militants loyal to the late Moammar Gadhafi seized control of the Great Man-Made River, a $33 billion project that taps a vast acquifer under the Sahara desert to supply the entire country, Sept. 3.

They did so to secure the release of the daughter of Gadhafi's former spy chief, Abdullah al-Senussi, who's scheduled to stand trial for crimes committed during Libya's eight-month civil war in 2011 that toppled Gadhafi.

What made it doubly embarrassing for the government was that Anoud al-Sanussi, 22, was snatched Sept. 2 in an ambush in the capital by elite forces as police escorted her to the airport to board a flight to Sebha, hundreds of miles south of Tripoli, to join relatives there.

The government of Prime Minister Ali Zeidan settled the issue and restored control of the water supplies by the end of last week after Senussi's daughter was released unharmed Sunday.

She had been seized less than 100 yards from Tripoli's al-Rayoumi where she had served a 10-month sentence for entering Libya with a forged passport in October 2012.

The group that abducted her, the First Special Reinforcement Unit, is under the command of the Supreme Security Committee established by the Interior Ministry.

Many of its personnel fought against the regime and helped depose Gadhafi. They said the grabbed Senussi "for her own protection."

The ease with which the militants seized a key pumping station in the southern Libyan desert underlined the vulnerability of the vast water system, arguably the crowning glory of Gadhafi's harsh 42-year rule, and other essential infrastructure.

Water Resources Minister Alhadi Suleiman Hinshir, who flew south to negotiate with the militants, said Tuesday it will take several days before the system will be able to pump at the pre-attack rate of 45.8 million cubic feet of water per day to Tripoli.

The current flow is around 7 million cubic feet a day.

The capital, with a population of about 3 million, depends on the Great Man-Made River, or GMMR, and related infrastructure for its fresh water.

The problem for Zeidan's government is that much of the system passes through regions controlled by armed groups hostile to Tripoli. This, the U.S. private global intelligence consultancy Stratfor observed, "is a challenge that post-Gadhafi authorities have not been able to fully address."

The militants who seized the pumping station on the western branch of the GMMR in the Sebha region were from the Magraha tribal grouping, which is loyal to the Senussis.

They stormed the facility at Shuwair, which is reportedly guarded by their clansmen, rather than the main pumping station at Jebel al-Hasauna in the Gera region because it is well protected.

This isn't the first time the GMMR has been targeted.

In September 2011, toward the end of the Libyan conflict, Gadhafi's retreating loyalists cut off water supplies to Tripoli, then held by rebel forces who were battling to gain control of the strategic southern water-producing centers. Overcoming that water crisis was a major challenge for the rebels' National Transitional Council, as it is today for Zeidan's government.

For a time, Gadhafi's loyalists held two cities that control the water supplies from the GMMR, Sirte, Gadhafi's hometown on the Mediterranean coast in the north, and Sebha in the south. They were eventually overcome, but Zeidan's government has not been able to secure the water system sufficiently since Gadhafi's ouster, underlining just how chaotic things are Libya and are likely to remain so for some time.

The GMMR was hailed an engineering masterpiece when it was completed in the 1990s after more than a decade of construction. Before the war, it provided 175.6 million cubic feet of water a day for cities on the coast where most of Libya's 6.5 million people live.

The system tapped into the vast underground Nubian Sandstone Aquifer, the largest in the world, which was discovered in the mid-1950s by Western oilmen.

It covers 772,000 square miles at a depth of 1,600-2,500 feet under the desert. The water is carried through a network of gigantic concrete tunnels about 3,125 miles long and buried 10-12 feet under the sand.