Nigeria -- For years, villagers who lived near the Alau dam in northeastern Nigeria had told government officials that the structure was broken and the reservoir behind it too full.
But in early September, after heavy rains, a half-dozen officials stood overlooking the brimming reservoir, their feet squelching in the mud as they tried to reassure Nigerians that the dam was in good condition.
"The dam is not broken," Alhaji Bukar Tijani, the government official leading the delegation, said that day. "People should not be afraid."
Four days later, water ripped through the Alau dam wall, leaving two-thirds of the city of Maiduguri underwater, killing up to 1,000 people, said rescue and security workers, and displacing nearly a half-million others.
After the disaster, government officials blamed God, climate change and the poorest people of Maiduguri, who they said had put themselves in harm's way by living in cheap homes along the Ngadda River.
But, in fact, government agencies knew the dam was badly damaged and did not fix it or correct operational mistakes despite repeated warnings, both from local residents and from engineers who spent six years studying the dam.
Eight months before the dam collapsed, one of the engineers, Mala Gutti, warned dam officials that the structure was under intense hydraulic pressure and at risk of "catastrophic failure."
The officials replied that they already knew of the problem and were taking action, Gutti said in an interview. The Nigerian media found budget lines showing that money had been repeatedly allocated for rehabilitating the dam. But locals said nothing had been done to either fix it or reduce the pressure it was under.
"They are really incompetent, I'm sorry to say," said Gutti, who carried out the research with colleagues at the University of Maiduguri. "They don't know what they are doing."
The government's failure to prevent the Alau dam disaster has raised concerns about more than 300 other dams "in dire need of maintenance" in Nigeria, according to Connected Development, a local nongovernmental organization.
Even local authorities said Maiduguri should serve as a warning: "Other people should learn from Alau dam," said Alkali Lawan, an official with the Ministry of Water Resources in Borno state, of which Maiduguri is the capital. "It's a very big disaster."
Don't Panic
It rained hard in northeastern Nigeria in August. But because the government said there was no danger, many residents did not move. Many lived downstream of the dam in Maiduguri, an ancient center of learning battered in recent years by violence from insurgents with the extremist group Boko Haram.
Water burst through the dam around midnight one night in September, then rushed toward the city.
As the water crept into her home, Adama Ibrahim, a tailor and candy seller, knew she had to get herself and her 4-year-old son, Mahmud, out. She scrambled together a few of her belongings and made a run for it, heading for a nearby bridge.
In an instant, she said, "the water rose from my knee to my hip to my chest to my neck."
All she could do was try to keep Mahmud's head out of the water, hugging his small body to her chest, and pray for rescue.
Help took hours. When it came in the form of a few men with a truck, they would take only children. Ibrahim handed over Mahmud, a clingy, affectionate toddler, with no idea if either of them would survive.
"Just go," she told her son.
When she was finally thrown, half-drowned, into a rescue truck, she saw a woman and a child crushed to death by panicked people crowding into the vehicle, she said.
All around them, the city was in a frenzy.
Fishermen by the dam capsized and drowned in the surging water. One woman described seeing dozens of her neighbors, including children, swept away to their deaths as they tried to flee. Disabled people who once begged outside government offices vanished.
Ibrahim scoured the devastated city looking for Mahmud. She felt she was losing her mind. After three days, she finally found him.
Nigeria's emergency management agencies have refused to release a death toll, but according to community members, rescue workers and security personnel unauthorized to speak publicly, it is as many as 1,000.
Raising the Alarm
Most people in Maiduguri had no experience with serious flooding. The city, just on the edge of the Sahel, is arid for much of the year. Water came from the small Alau dam, which was constructed of masonry and earth in 1985 by a Greek contractor for the federal government, with the promise of improving the water supply to Maiduguri and nearby farmland.
Villagers in the community of about 2,000 who lived alongside the dam and fished in its waters knew when they saw a problem.
In 2021, they said a crack appeared in the dam's earthen embankment, and then the concrete channel designed to allow surplus water to flow out began to collapse. They alerted officials about the dam's degraded state and the need to release more water. They told the local government council, the military, the federal agency responsible for monitoring, maintaining and repairing the dam, and just about anyone else who would listen.
"We've complained so many times," said Shettima Mohammed, 70, a farmer and fish dealer from the village of Lawajeri. But he and other villagers said authorities either dismissed their warnings, made excuses for not taking action or occasionally delivered sandbags in a futile attempt to fortify the damaged embankment.
The villagers were not the only ones raising the alarm.
Gutti began studying the dam in 2017. He and his team found that the agency overseeing the dam -- the Chad Basin Development Agency -- had spent years, possibly decades, letting the dam overfill before opening its sluice gates.
The first principle of dam safety is to not let it overfill, Gutti said. But according to his research, this was done over and over again, putting the dam under intense hydraulic pressure.
"Every year, they repeat the same mistake," he said in an interview.
Adding to the pressure that the dam was under, the agency had let it fill with silt, the engineers said, meaning there was much less room for rainwater. These circumstances caused the dam to crack and crumble, Gutti said.
In a phone interview, Mohammed Zannah, the acting managing director of the agency, acknowledged that the dam had been damaged for several years. He confirmed that the sluice gates were only opened and closed once a year and said his agency did not have enough money for dredging.
But he denied that the reservoir had ever overfilled, that he received warnings from the engineers and that the dam had collapsed in the flood. Instead, he claimed that the obliterated earthen embankments were not part of the dam, as they were not made of concrete. He also defended having told the public that the dam posed no danger before the flooding.
He blamed the flood on increased rainfall caused by climate change.
Running Out of Water
Humanitarian agencies and government officials have warned that the next disaster facing Maiduguri will be severe water and food shortages.
Crops that would have fed 1.6 million people for six months were lost in the flood, according to Chi Lael, a spokesperson for the United Nations World Food Program. And with the dam broken, farmers say there will not be enough water to grow next season's rice, sorghum and sweet potatoes.
Now, residents of Maiduguri must rely for survival on the few working boreholes that are not contaminated with floodwater.
Officials have descended on the Alau dam since the disaster, promising its rehabilitation or reconstruction. Nigeria's president, Bola Tinubu, has said integrity tests will be done on all the country's dams.
"We are giving assurance to Nigerians that this is going to end well," Joseph Utsev, minister of water and sanitation, said this month at a meeting of a new committee tasked with evaluating Nigeria's dams.
For residents of Maiduguri, the aftermath of the flooding has become another tragedy with which to contend. The area is home to hundreds of thousands of people who fled Boko Haram in recent years after it murdered and kidnapped tens of thousands of people.
One of those survivors of Boko Haram, Fatima Mala, clung to a tree with her children in the hours after the dam broke, certain they would all drown. But she managed to keep them alive until they were rescued.
Since the flood, Mala and her family have been sleeping on a highway center divider -- the highest ground they could find. Her husband sold their phone for $2.50 to buy food for the children. It was their last possession.
As she waited in line recently for a cash handout from a Catholic humanitarian agency, Mala wondered how they would survive. The family prepared to move back to the tarpaulin tent they had lived under for six years, now half-wrecked and covered in mud.
She has no idea how they will get water.
Even before the flood, her family used to beg for it from nearby houses with boreholes. Now, those boreholes are all contaminated.
"With Boko Haram, once you've fled, you can sleep. With this, our chances of survival are slim," she said. "For me, the flood is worse than Boko Haram."