The giant wall that President Donald Trump wants to build on the border with Mexico will cost billions of dollars, disrupt numerous communities and sever the migration routes of hundreds of wildlife species.
The wall, intended to halt illegal immigration, would also block many rivers and streams. This consequence has not yet been discussed much. The wall itself could restrict water flow important to farms and cities on both sides of the border. This could worsen water pollution and lead to flooding disasters. It might also change groundwater recharge in areas fed by rivers.
All this, in turn, could affect treaties and water-sharing agreements along the border — both internationally and between neighboring communities within the U.S.
The wall has an estimated construction cost of $20 billion. But there are likely to be additional long-term costs from consequences that are difficult to imagine. To help understand these consequences, Water Deeply recently spoke with Bob Irvin, president of American Rivers, an environmental group that works to protect rivers across the U.S., including the Mexico border region.
Water Deeply: How might a border wall affect rivers and watersheds?
Bob Irvin: Just to give an example, along the border between Mexico and Texas, the Rio Grande River is the international boundary, and the boundary runs down the middle of the river. So if we’re going to build a wall, we have to decide: Are we going to try to build it in the middle of the river? That’s not a very practical solution. Would we put it on Mexican soil? I doubt Mexico would agree to that. Or would we put it on Texas soil, and cede our right to use the river in that area?
There are some very practical problems just with the physical act of building a wall. In addition to that, there are problems with what it would mean for the rivers themselves, as well as the wildlife that depends on those rivers.
With the type of wall that’s being discussed, along a river you basically are building a dam. It’s a dam that parallels the river [on the Rio Grande]. But in a storm event, what you’re going to have is all the rushing water and debris that’s going to pile up against that wall, probably tearing out sections of it. That’s what is happening along some sections of wall that already exist in Arizona. And you’re just going to have a constant problem with debris piling up and impeding the flow of the river.
In addition to that, in the arid Southwest, rivers are literally the lifeblood of the region. So, naturally, wildlife use rivers as corridors to move. And wildlife doesn’t know where an international boundary exists. They just move along a river and if you build a wall along there you’re going to impede those migrations. Some of these species, like jaguars, are endangered and are already in bad shape. Building a wall is just going to make things worse for them.
Water Deeply: How could a border wall affect our water treaties with Mexico?
Irvin: The issue of treaty rights to water between the U.S. and Mexico is a major issue in considering whether to build a wall. For example, on the Colorado River, the river flows across the border when there’s enough water in it. It doesn’t always make it to the Sea of Cortez. In fact, it rarely makes it. Yet we’re obligated to deliver something like 1.5 million acre-feet (1.9 billion cubic meters) of water to Mexico by treaty. If you build a wall there, you’re going to have to have some mechanism for allowing that water to pass through. Then that raises questions about how secure is your wall in the first place.
Also, given the poor relationship that the Trump administration has started with Mexico, it’s difficult to see that the Mexican government is going to be in a particularly flexible mood in terms of negotiating water agreements – or renegotiating them – in the face of this effort to build a wall that Mexico clearly doesn’t want either.
And on the Rio Grande, we need to remember that the reason the Rio Grande has water flowing below El Paso, in Texas, is because the Rio Conchos in Mexico is the huge tributary. So the water that’s in the Rio Grande along much of Texas is actually water that comes from Mexico. Because we use the full amount of the Rio Grande above El Paso for irrigation and other uses, Texas irrigators who rely on water from the Rio Grande below El Paso need the cooperation of Mexico to ensure they continue to have water.
Water Deeply: What about water quality? Could a border wall lead to more pollution of surface water or groundwater?
Irvin: Building a wall is going to have an effect on the flow of rivers, wherever it exists. And when you change the flow of a river, you’re changing the natural cleansing mechanisms of that river. So you certainly could see a buildup of pollutants – both solid and chemical – as a result of that.
Water Deeply: Will these things be taken into account if the wall gets built?
Irvin: The problem is that the effort to build a wall is also going to include, undoubtedly, provisions to exempt construction from the requirements of environmental laws, such as the National Environmental Policy Act or the Endangered Species Act. All of the legislation in the past on border walls, and certainly what this administration is contemplating, would exempt construction from those laws. So even though these are issues we ought to be thinking about carefully before we start building a wall along the border, the proponents of the wall want to make sure that environmental protection doesn’t get in the way of construction. It’s very worrisome.
There’s a Native American tribe along the border in Arizona (the Tohono O’odham Nation) and their reservation straddles the international border. They have no interest whatsoever in having a wall bisect their reservation. People who actually live right along the border are almost unanimously opposed to the idea of building a wall, because they recognize the implications.
Water Deeply: How many rivers and streams would be affected by a border wall?
Irvin: I couldn’t even give you an estimate. I’m sure it’s more than 100, and it might be as many as 500. There are an awful lot of little drainages that come across the border.
One is the San Pedro River in Arizona, which is actually a National Riparian Conservation Area. And it’s actually one of the few perennial streams that flows from south to north – out of Mexico and into the U.S. – and it’s an incredible area for birds and other wildlife. It’s an area where, even when the Bush administration was doing their stuff, they didn’t built a wall there. They put some fencing in and some vehicle barriers. But they recognized this was not an area that was a good place to build a huge wall.
Water Deeply: If the wall gets built, what are these border rivers likely to look like in the future?
Irvin: I think if we built a solid wall along the entire U.S.-Mexico border, it would have a drastic and harmful effect on the rivers and streams along the border and the wildlife and communities that depend on those rivers and streams. It would undoubtedly change the flow of those rivers and streams and it would also impair the water quality in them.
I’m sure it would change the course of streams, and you’d see areas that used to be stream beds that no longer are. I also think you would actually see species go extinct that now cross the border.
Water Deeply: Does the design of the wall matter? Would that make a difference for rivers or wildlife?
Irvin: No. Whatever kind of wall you build, it’s going to have some impacts. A wall of any kind is just not conducive to allowing water and wildlife to move back and forth across a border. The very fact that you have to sink posts in the ground to hold up sections of this wall is going to be disruptive in some fashion. Wildlife are going to encounter it and have to figure out: Is there a way around it, over it, under it?
Water Deeply: Can it be stopped?
Irvin: Certainly we’re going to work to convince Congress not to authorize the wall or appropriate money for it. There may be opportunities for litigation to challenge construction of the wall. [The Center for Biological Diversity and Rep. Raul Grijalva, D-Ariz., filed suit on April 12.] So there are things that can be done. But to be realistic, if Congress authorizes the construction of the wall and provides the money to do it, and the administration wants to do it, it’s going to be very difficult to stop.
Water Deeply: Should water agencies get involved in the opposition?
Irvin: Absolutely. I think it’s something that anyone who’s concerned about the health of rivers and water along the border ought to be paying attention to, and ought to be weighing into.
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