As Texas went dark, the lights in Presidio stayed on. Why?

Presidians had a lot of guesses for why they never lost power. Most of those guesses "are wrong," an AEP spokesperson said.

PRESIDIO — Infrastructure in Presidio isn’t always the most reliable. The city’s water system is overpressured, and the main pipelines are too small, frequently resulting in leaks and boil-water notices that last for hours or days.

But while much of Texas was without power, water or heat last week, not only did Presidio’s pipe stay largely intact — the power stayed on. Reached for comment last week, residents and officials in the city weren’t aware of a single residence that lost power during the winter storm, at least for any significant period of time. Some residents dealt with low water pressure, but no boil-water notices.

The good fortune likely saved lives in the border city, where some residents rely on powered medical devices like oxygen tanks, and where many others live in homes that aren’t equipped to handle extreme cold. Like cities across the region, temperatures dipped into the single digits last week. But the fortunes also left Presidio officials and residents with a lingering question: Why was Presidio spared the worst of a winter storm that devastated much of Texas, including parts of the tri-county?

As normal life continued in Presidio last week, theories abounded. Maybe solar facilities near Presidio had kept power lines humming. Maybe a massive sodium-sulfur battery in town had kept lights even when the rest of the power grid had failed. That “big ol’ battery,” or BOB, was installed in 2010 to combat frequent outages caused by a single transmission line into the city.

Maybe, some officials posited, it was because of an agreement with Mexican utility providers to borrow electricity for Presidio when the city went dark. But that agreement ended years ago, and Ojinaga also experienced rolling blackouts as subfreezing temperatures barreled down on the region. None of those theories fully explain why Presidio was spared from Texas’ power-grid failures, said Larry Jones, a spokesperson for AEP Texas.

“That sounds like a lot of suppositions,” he said when told about some of the prevailing theories in Presidio. “Most of them are wrong.”

To be clear, even AEP Texas may not fully understand why Presidio kept power. When the company receives orders to turn off circuits, as it did last week, the shut-offs must be “instantaneous” to prevent damage to the grid, Jones said. For that reason, the company relies on computers to make those quick decisions.

Still, the company inputs variables for each circuit, including details on critical infrastructure and the total expected power load. And that, Jones said, allowed the company to make some educated guesses about why Presidio’s power stayed on.

One local theory came closer than the others. Maybe, some locals theorized, Presidio had enough critical infrastructure to get classified as essential. After all, the city has one of the only ports of entry in Far West Texas, as well as housing and facilities for U.S. Customs and Border Protection.

In an interview, Jones confirmed that infrastructure was classified as critical. But even still, the mere existence of critical infrastructure alone wasn’t enough to guarantee power last week.

“It’s very difficult in some areas — if not impossible — to find a circuit that does not connect to at least one critical facility,” Jones said. Across Texas, “we did have some water plants that were out, as well as some hospitals. We made every effort to restore their power as quickly as possible.”

Instead, Jones pointed to other aspects of Presidio’s local power grid, including the single transmission line into town. Unlike in Marfa, where the company was able to turn off power for parts of the city, turning off Presidio’s circuit might have plunged the whole city into darkness.

Because Presidio has only one circuit — and because reaching the nearest towns and hospitals require an hour-plus drive along windy mountain highways — putting Presidio in the dark could have been catastrophic, he said. Unlike Marfa and Alpine, the city would have had no reliable warming station. “Every effort would have been made to keep that circuit off the list,” Jones said.

Besides, Jones said, Presidio just didn’t draw that much power compared to other circuits in the region. Even if AEP Texas had turned off the city, the company wouldn’t have gained much in terms of total megawatt capacity. It would have been a big loss for residents of the city, with little gain for the Texas power-grid at large.

Regardless of the exact reasons for why computer programs kept on the lights in Presidio, residents and officials in the city were grateful for the decision. Malynda Richardson, the city’s EMS director, said the decision may have literally saved lives.

In Houston, where residents experienced widespread outages, Richardson’s 94-year-old mother lost power at her house. Richardson’s sister had to take her to the emergency room, just so they could keep her oxygen tank running. If a similar situation had unfolded in Presidio, residents may not have been able to get to a hospital in time.

The city’s public school system has a generator, Richardson said, which residents could have used to stay warm and charge devices. But it’s unclear how long that generator would have lasted if all the rest of Presidio went dark, nor what people would have done in a true medical emergency. Case in point was the hospital transport to Big Bend Regional Medical Center in Alpine that EMS workers had to do in the middle of the winter storm. In the blur of last week, Richardson couldn’t remember exactly when the transport happened. For medical-privacy reasons, she couldn’t give many other details, either.

Still, the trip was a reminder of how far Presidio residents live from essential, sometimes life-saving, services. And when U.S. Route 67 to Marfa turns icy, those trips take even longer. “I think they were going around 40 miles per hour,” Richardson said of that ambulance. And that was only after she had called the Texas Department of Transportation, to make sure steep parts of the road were passable at all.

More than anything, though, Richardson said the same factors that have made Presidio so vulnerable to the coronavirus pandemic — poverty, ethnic background and an aging population, to name a few — could have left residents struggling during the winter storm. Around 40% of Presidio residents live below the poverty line, according to census figures, and around 96% of residents are Latino — a demographic group that’s been disproportionately affected by the coronavirus pandemic.

As reports of outages came in from across the state, Richardson said she wasn’t primarily worried about people on oxygen — there were just a dozen or so in Presidio, she said. Instead, she worried about people in non-weatherized homes.

Many homes in Presidio “don’t have anything for heat other than a little electric space heater. I was in one just recently where you can see daylight through a crack in the cinderblock wall,” Richardson said. “If the electricity went out, those people would have been in a world of hurt. They would not have been able to stay in their homes.”