The successful evacuation of large areas of Texas in preparation for Hurricane Harvey, which is expected to make landfall early Saturday morning and could cause devastating amounts of damage, depends on Texans putting their lives in the hands of the government. A White House statement issued Friday urged residents to “heed the advice and orders of their local and State officials”; the president’s homeland security adviser, Tom Bossert, said that “now is not the time to lose faith in government institutions.”

But many of the Texans living in the hurricane’s path are unauthorized immigrants, who have very good reasons not to trust government in general, and the Trump administration (and Texas state government under Gov. Greg Abbott) in particular. And even with Harvey gathering speed in the Gulf of Mexico, the government is sending mixed messages about whether it wants to save immigrants or deport them.

Customs and Border Protection will continue to operate roadside checkpoints within 100 miles of the US-Mexico border during the evacuation. They’ll only close a checkpoint if it’s in the hurricane’s path and the highway it’s on is closing.

The state of Texas, which has announced that it won’t be checking the legal status of people who check into emergency shelters, and the federal government have both stressed that the “highest priority is the safety of the public.” But in practice, having a top priority sometimes means putting other priorities aside. And cracking down on immigration, in particular, is the sort of agenda that can easily make other government priorities harder to execute — when the government suddenly needs unauthorized immigrants to trust it, after giving them every reason in the world not to.

Unauthorized immigrants won’t be asked for IDs at shelters — but could be stopped en route by Border Patrol

The last time Texas was hit by a major hurricane — Hurricane Ike, in 2008 — the message sent by Homeland Security Secretary Michael Chertoff was clear: Residents should be able to evacuate without worrying they’d be stopped at a checkpoint, because Border Patrol agents wouldn’t do anything to impede a speedy evacuation of the area.

The Bush administration didn’t shut down the checkpoints entirely. But Chertoff instructed agents, "We're not going to be bogging people down with checks or doing things to delay the rapid movement of people out of the zone of danger." (The announcement was celebrated by then-Texas Gov. Rick Perry; a spokesperson for Perry said that it would be “nonsensical” to keep checkpoints operating at their typical pace during an evacuation.)

The message sent by the Trump administration is very different. “The Border Patrol is a law enforcement agency and we will not abandon our law enforcement duties,” said a statement from the Rio Grande Valley Sector office Thursday that announced that checkpoints would remain open. And while a spokesperson for the sector clarified that “we’re not going to impede anybody getting out of here,” that assurance was absent from a statement issued from Customs and Border Protection headquarters on Friday:

U.S. Border Patrol checkpoints in the path of Hurricane Harvey in Texas will close as state highways close. These closures will occur in a manner that ensures the safety of the traveling public and our agents. Border Patrol checkpoints that are outside of the path of the hurricane will remain operational. CBP will remain vigilant against any effort by criminals to exploit disruptions caused by the storm.

It’s possible that in practice, Border Patrol agents at checkpoints will conduct speedier or less frequent checks than usual in the interest of keeping the evacuation moving. But the concern is only in part about what is actually happening; it’s partly about what unauthorized immigrants in the path of the storm worry will happen.

Border patrol agents in the Rio Grande Valley told Vox earlier this month that unauthorized immigrants who live in their communities tend to know where the checkpoints are and avoid them. That’s not necessarily possible during a hurricane evacuation. Given the choice between sticking out the storm and risking arrest and deportation to escape it, it’s entirely possible many Texans will choose not to leave.

Immigrants under Trump — and in Texas — were already dealing with a deficit of government trust

To a certain extent, the checkpoints are undermining a federal and state attempt to get unauthorized immigrant Texans to feel just as safe evacuating as everyone else. Gov. Abbott has said that state officials won’t check legal status at emergency shelters, and CBP issued a joint statement with Immigration and Customs Enforcement (ICE) on Friday saying that “Routine non-criminal immigration enforcement operations will not be conducted at evacuation sites, or assistance centers such as shelters or food banks.”

But even if Border Patrol were following their lead and closing the checkpoints, it’s not clear how successful the evacuation of Texas’s unauthorized immigrant population would be. Because both the Trump administration and the state of Texas are struggling to overcome, for the sake of hurricane preparation, the signals they’ve sent unauthorized immigrants for months: to stay away from government.

Unauthorized immigrants are often wary of seeking government assistance even in the best of circumstances, and their isolation can keep them from finding out important information: Many immigrant residents of Flint, Michigan, for example, found out about the prohibition on drinking the city’s lead-contaminated water months after the rest of the city did. High-profile immigration enforcement makes that even harder.

After an immigration raid in Austin in February, school attendance briefly plummeted; local immigrant-patronized businesses took weeks to recover, as immigrants slowly became comfortable leaving their homes. Similar things have happened in other communities around the US.

Many local officials have tried to counteract the fear of government instilled by the federal immigration crackdown. But in Texas, those efforts have been systematically undermined by the state government — whose “anti–sanctuary cities” bill doesn’t just punish city police departments for declining to assist with federal immigration enforcement but allows any police officer in Texas to ask people about their immigration status during operations.

That bill, SB 4, is set to go into effect September 1. Once that happens, an unauthorized immigrant going out in public will be a risk — and any interaction with a police officer could start a one-way track to deportation.

And yet a week before that happens, the state of Texas is asking immigrants to trust the state with their lives.

The Trump administration’s dedication to cracking down on immigrants limits its effectiveness in other areas

The definition of an emergency is that business cannot continue as usual — that certain things have to be stopped or suspended because they distract from, or undermine, the goal of saving lives during a natural disaster and rebuilding property afterward.

Immigration enforcement is often one of those things that has to be deprioritized. Border Patrol agents have to assist with rescue and recovery when natural disasters take place on their turf. Sometimes rules have to be bent or waived to make sure storm victims aren’t victimized twice: The Bush administration allowed international students affected by Hurricane Katrina to apply for deferred action as a protection from deportation, for example.

And the work of rebuilding a community often (as it did after Katrina) physically relies on immigrant labor, supplied by contractors who don’t always have the resources to check everyone’s papers — or the manpower to rebuild what’s needed with citizens alone.

It’s a simple reality of triage: Having a “highest priority” means other priorities have to be, temporarily, demoted.

The Trump administration, however, has made its immigration crackdown the centerpiece of its agenda. Immigration has been the issue the president returns to whenever he’s feeling thwarted; it’s the one thing his otherwise understaffed executive branch has most thoroughly repudiated his predecessor’s policy on.

That crackdown entails trade-offs for public trust in government. It was clear when police departments around the country saw a drop in the number of Latina women reporting domestic violence — while reports from white women didn’t change. It is clear again now, with the evacuation.

In both cases, administration officials have simply declared that people ought to trust the government to do the right thing. Interim ICE Director Tom Homan has said that no one should be afraid to report a crime; when asked about the checkpoints in the Harvey evacuation, Bossert, the homeland security adviser, said Friday that “people shouldn’t be fearful about going to a shelter and getting food and water.”

Telling people they shouldn’t be afraid of something doesn’t stop them from fearing it — especially if they have good reason for their fear. Trust in government isn’t something that can be turned off and on like a spigot. And moments like this are exactly the time when it becomes clear how hard it can be for government to save people, when it’s worked so hard to persuade them the government wants to punish them.