Half of Puerto Rico was in the dark Wednesday after a tropical storm lashed the island archipelago with torrential rain and wind, damaging a power grid that has struggled to recover from repeated storms.

Luma Energy, the private consortium operating Puerto Rico’s electricity transmission and distribution, reported that more than 700,000 of its nearly 1.5 million customers were without power – meaning 50% of the system was offline as of Wednesday afternoon. Culebra and Vieques, two small islands off the east coast, are experiencing near-total blackouts.

The power outages were a reminder that Puerto Rico’s electrical grid remains prone to collapse nearly seven years after Hurricane Maria pummeled the island chain as a Category 4 storm. Thousands of people died, some from waterborne disease outbreaks when the power and water weren’t restored for months after the storm.

Since then, far less powerful storms have continued to wreak havoc. Hurricane Fiona hit Puerto Rico as a Category 1 storm and knocked the power grid offline in 2022.

“It’s disappointing and it’s concerning that the grid is down again, given that this is just a tropical storm,” said Charlotte Gossett Navarro, Puerto Rico chief director for Hispanic Federation, a nonprofit that has helped promote solar energy in vulnerable communities.

Ernesto battered Puerto Rico as a tropical storm on Wednesday and strengthened into a Category 1 hurricane as it moved toward Bermuda. It dropped more than 10 inches of rain in some areas, and downpours were expected to continue into the afternoon. Emergency officials were watching the water levels of several rivers on the brink of flooding, particularly in eastern Puerto Rico, and preparing for the possibility of landslides.

The lack of electricity poses a particular threat to energy-dependent individuals, especially older adults who need power for certain life-sustaining treatments. It also interrupts water service to homes throughout the archipelago, some of which depend on a series of powered pumps to deliver it.

In recent years, the government has tried to position backup generators to supply power to water plants during outages, but the rollout of that program has been haphazard and hampered by operational failures.

Puerto Rico Gov. Pedro Pierluisi said at a Wednesday news conference that he has asked the president of Luma to restore power “as quickly as possible.” He added that President Joe Biden approved a disaster declaration for the U.S. territory, unlocking assistance from the Federal Emergency Management Agency.

“We want that number of customers without service to go down,” Pierluisi said. “But it’s difficult to say when 100% of customers will see power return because personnel are on the ground assessing that now.”

A Luma Energy spokesperson told The Washington Post that the utility’s crews were prepared and in communication with regional operation centers to complete damage assessments as the weather permits. So far, the damage appears to have been caused by tree limbs tearing down power lines and strong winds toppling lines into one another, automatically shutting them off.

At least one major transmission line, which had been serviced a month before the storm, went offline without explanation, shutting down power for Cayey, a city in the central mountains, and several municipalities to its south, including Santa Isabela.

So far, no deaths related to the storm have been reported.

Miraidaliz Rosario Pagán, mayor of Naguabo, a southeastern municipality known for flooding, said her entire community of about 23,000 people has been without power since 2:30 a.m. Wednesday, and that at least four barrios consisting of hundreds of families have no running water. More than 10 inches of rain fell overnight and into the morning hours, but she said rivers are starting to recede to normal levels.

Despite efforts to improve service, Rosario Pagán said electricity remains unreliable for her community. After she complained to Pierluisi in a phone call Wednesday morning, she said, representatives of Luma called to set up a meeting. The cause of her town’s blackout is unclear, but there are dozens of toppled trees and power lines littered throughout roadways.

A large portion of Naguabo residents are older adults. That is the case in many towns throughout Puerto Rico as young people leave for the mainland in search of better work opportunities. Rosario Pagán said she has worked to make special accommodations for seniors when storms approach, knowing that they are likely to be without power for an extended period.

Ahead of Ernesto, workers took an inventory of the treatment and medication needs of various residents, and Rosario Pagán’s office distributed more than 200 small solar batteries and panels to specific energy-dependent households.

“Electric power is an essential service that is critical to the quality of life of people here,” Rosario Pagán said. “With the high rates we pay as Puerto Ricans, and we’ve seen eight rate hikes in recent years, it’s worrisome that we still receive such poor service.”

A generator is powering the lone medical clinic in Naguabo, but so far the mayor said they have not reported any health emergencies. The local government also leases power inverters to residents who need them, but they have a limited supply.

“We have some options available to residents while they are without power,” Rosario Pagán said, “but this cannot go on long.”

After Fiona in 2022, U.S. Energy Secretary Jennifer Granholm traveled to the archipelago several times to help ease the flow of billions in federal grant dollars toward resiliency projects that prioritize energy sources such as solar. But while Puerto Rico has progressed on that front, it is far from its projected goals to transition to 100% renewable energy by 2050.

Separately, the federal government has assigned more than $12 billion in disaster funding to modernize the fossil fuel-powered grid and strengthen its resiliency. Since Maria, Puerto Rico has privatized the grid, contracting Luma to take over control of power lines and transmission towers on the islands while Genera PR, another contractor, operates power generation plants.

The longer the power is out, the more lives are at risk in Puerto Rico, said Gossett Navarro, of the Hispanic Federation. Her organization has received and invested millions of dollars through a U.S. Department of Energy program and philanthropic endeavors to install rooftop solar energy systems in low-income homes and community centers.

“The piece that is important is how quickly are they are going to get these people back online,” she said from San Juan. “The longer we’re without power, the more of a disaster this becomes.”