"There's an ebb and flow," said Marine Capt. Glen Baker, one of a small group of Marines who continue to hold an outpost in Kajaki and advise Afghan forces in the area. "There was an increase when the Marines pulled out and there has been a decrease subsequently."
The company working on building the dam has also been able this year to send supplies via road — four convoys of trucks have made the trip without incident. Previously, equipment was being helicoptered in at enormous cost.
The core of the project is the installation of a third power-generating turbine at the dam, an effort that planned since 2002. The installation was originally budgeted at $18 million. Now it is getting another $85 million and is scheduled to be installed in March, after being delayed by efforts to weed out subcontracting applicants suspected of having Taliban ties.
But many in Afghanistan have already given up on Kajaki.
"It is 10 years now that Kajaki dam has been as it is. Too much money has been spent there in the name of reconstruction ... all of that money wasted," President Hamid Karzai said in a speech in December.
Shah, the construction worker, echoed the complaint.
"When the international forces first came here they told us, 'In one year you will have the dam, you will have power, you will have roads.' But that didn't happen. ... and we are still waiting," he said.
Even if the project now overcomes the security and logistical barriers, there are questions about whether it's worth the cost.
The dam can't provide enough power to sustain the main city in the region — Kandahar — and the price tag is steep for the extra irrigation it brings to the Helmand River valley.
And there are also signs of the difficulties the Afghan government may face when it takes over the management of the dam.
One area already controlled by the Afghans is the management of irrigation water. The water has to hold to a certain level through the winter to keep electricity flowing, but last year the manager in charge of irrigation yielded to pressure from farmers and kept the water valve open.
"He ignored the need to close it in September. So the level of water was reduced," said Shaqib Nassar, the utility's chief operations officer, which oversees the dam. As a result the dam can only produce 24 megawatts, rather than 33 megawatts, he explained.
And the Special Inspector General for Afghan Reconstruction, the U.S. government watchdog for spending in the country, said in a report in December that $12.8 million in electricity distribution equipment provided to the Afghan energy utility in Kandahar was sitting unused because the Afghan staff "lacked the technical and operational capacity to properly install and manage it." The Kandahar utility also oversees Kajaki dam.
As recently as mid-2012 the U.S. was considering scrapping the whole project and switching the money to less unwieldy projects. Then it doubled down.
"Several months back we had a lot of discussion about whether continued investment in this would be worthwhile ... There are certainly voices that say, 'We've invested this much, let's finish it,' and there are others that say, 'We've invested this much, however the additional investment just won't get us there,'" said Yamashita, the USAID official.
"In the end, the discussion and the conclusion was that the output of electricity plus the development programs in the Helmand valley, plus the security it brings, equals a risk worth taking."
From the air, the Helmand River is a narrow turquoise ribbon through the desert. The dam is a stacked concrete wall that bisects the river, creating a reservoir ringed with trees — a few spots of green in a vast field of brown.
The helicopters that fly to the dam are owned by a U.S. contractor and depart from a U.S. military base. As resources and Americans become fewer, the U.S. Army Corps of Engineers and USAID say they expect oversight to depend increasingly on Afghan partners. Everyone says they are committed to finishing the project; they'll just have to manage much of it from afar.