BAGHDAD—In its largest reconstruction effort since the Marshall Plan, the U.S. government has spent $53 billion for relief and reconstruction in Iraq since the 2003 invasion, building hospitals, water treatment plants, electricity substations, schools and bridges.

But there are growing concerns among U.S. officials that Iraq will not be able to adequately maintain the facilities once the Americans have left, potentially wasting hundreds of millions of dollars and jeopardizing Iraq's ability to provide basic services to its people.

The projects run the gamut—from a cutting-edge, $270 million water treatment plant in Nasiriya that works at a fraction of its intended capacity because it is too sophisticated for Iraqi workers to operate, to a farmers' market that farmers have not been able to decide how to divide up space for, to a large American hospital closed immediately after it was handed over to Iraq because the government was unable to supply it with equipment, a medical staff or electricity.

The concern about the sustainability of the projects comes as Iraq is preparing for pivotal national elections in January and as rebuilding has emerged as a political imperative in Iraq, eclipsing security in some parts of the country as the main anxiety of an electorate frustrated with the lack of social, economic and political progress. U.S. forces are scheduled to begin withdrawing in large numbers next year.

In hundreds of cases during the past two years, the Iraqi government has refused or delayed the transfer of U.S.-built projects because they cannot staff or maintain them, Iraqi and U.S. government officials say.

Other facilities, including hospitals, schools and prisons built with U.S. funds, have remained empty long after they were completed because there were not enough Iraqis trained to operate them.

“;As large-scale construction projects—power plants, water-treatment systems and oil facilities—have been completed, there has been concern regarding the ability of Iraqis to maintain and fund their operations once they are handed over to the Iraqi authorities,”; said a recent analysis prepared for Congress by the Congressional Research Service.

The Government Accountability Office and the special inspector general for Iraq reconstruction have also issued reports in the past several months about the potential failure of U.S.-financed projects once they are transferred to Iraq.

Stuart W. Bowen Jr., inspector general for Iraq reconstruction, said his agency had “;regularly raised concerns about the potential waste of U.S. taxpayer money resulting from reconstruction projects that were poorly planned, badly transferred, or insufficiently sustained by the Iraqi government.”;

The blame is shared, officials said. While Iraq has often been guilty of poor management, U.S. authorities have repeatedly failed to ask Iraqis what sort of projects they needed and have not followed up with adequate training. And whether or not the U.S.-built health centers and power plants are ever used as intended, the U.S. companies that won the lion's share of rebuilding contracts from the federal government have been paid.

The Iraqi government, prodded by U.S. officials here, has pledged to begin spending more of its own money on reconstruction, but the country is facing a substantial budget deficit because of declines in international oil prices.

Prime Minister Nouri Kamal al-Maliki has insisted that reconstruction is the next task. What is not clear is where the $400 billion the government says it needs will come from.

“;We will use the revenue we have from oil, but the government feels it has to do more than that to rebuild,”; said Ali al-Alak, an adviser to al-Maliki.

In the meantime, the American—military and civilian reconstruction specialists—continue to depart in large numbers, taking with them their money, equipment and expertise.

Despite the $53 billion spent by the United States, many Iraqis have criticized the rebuilding effort as wasteful. Ali Ghalib Baban, Iraq's minister of planning, said it had had no discernable impact. “;Maybe they spent it,”; he said, “;but Iraq doesn't feel it.”;

Iraqis, for whom bombed-out buildings are an unremarkable part of urban existence, also say they have seen little evidence of rebuilding.

“;Where is the reconstruction?”; asked Sahar Kadhum, a resident of Kut, about 100 miles southeast of Baghdad. “;The city is sleeping on hills of garbage.”;

Indeed, despite the billions in U.S. funds, more than 40 percent of Iraqis still lack access to clean water, according to the Iraqi government. Ninety percent of Iraq's 180 hospitals do not have basic medical and surgical supplies, according to the aid organization Oxfam. Iraqis also have disproportionately high rates of infant mortality, cerebral palsy and cancer.

Exacerbating the problem, Iraqi and U.S. officials say is that hundreds of thousands of Iraq's professional class have fled or been killed during the war, leaving behind a population with too few doctors, nurses, engineers, scientists and others.

In Hilla, 60 miles south of Baghdad, a recently completed $4 million maternity hospital built by the Americans is open, but the staff members are unable to operate much of its equipment.

“;The building is fairly good and the Americans have provided the hospital with a variety of high-tech medical devices, but they did not pay attention to the training of doctors in how to use them,”; said Jawad al-Jubouri, a district officer.

In Fallujah, west of Baghdad, a $98 million wastewater treatment plant built by the United States serves only one-third of the homes it was intended to because the Iraqi government has not supplied it with sufficient fuel, “;raising the possibility that the U.S. effort has been wasted,”; according to a special inspector general's report.

At Ibn Sina Hospital in Baghdad, which had been the U.S. military's largest medical center in the country, Iraqi security forces took up guard positions even before the conclusion of a ceremonial transfer to the Iraqi government last month. The hospital, however, has been closed because the Health Ministry lacks the staff and equipment to reopen it, even though the U.S. military said it left $7.9 million in equipment behind.

Iraq's most notorious reconstruction project might be the $165 million Basra Children's Hospital in southern Iraq. Championed by Laura Bush when she was the first lady, its completion has been delayed by more than four years, and the project is $115 million over budget.

Once the hospital opens—perhaps next year—there will be too few doctors and other medical staff members to take advantage of much of its modern equipment.

“;It was supposed to open in March, but I don't think it will be ready,”; said Ahmed Qassim, the hospital's director. He added: “;Maybe July, but we don't know. Maybe not July.”;