STEVE INSKEEP, HOST:
President Trump's declaration of a national emergency at the southern border did not end the debate over the wall that he wants to build. There is plenty of discussion about how much walls would really affect the flow of people and goods. Those who live near the border raise an entirely different concern - how would walls affect the environment and the movement of animals? The border crosses through wildlands and touches six national parks. Mallory Falk of our member station KRWG reports from Santa Teresa, N.M.
MALLORY FALK, BYLINE: At first glance, the Chihuahuan Desert seems, well, deserted - mostly sand spotted with mesquite and soaptree yucca. But it's actually home to lots of wildlife - jack rabbits, coyotes...
LAIKEN JORDAHL: Mountain lion, like, foxes and even endangered species like the Mexican gray wolf.
FALK: Laiken Jordahl is with the Tucson-based Center for Biological Diversity.
JORDAHL: All sorts of animals have evolved for millennia untold to migrate freely through the desert. And now we have this really landscape-scale obstruction that will stop all species in their tracks.
FALK: Jordahl stands in front of that obstruction, a 20-mile-long steel fence near the Santa Teresa Port of Entry. Last year, it replaced waist-high vehicle barriers that didn't block migration. The U.S.-Mexico border is ecologically diverse. Here in southern New Mexico, it's scrubland. But keep traveling, and you'll hit forest, wetlands and salt marshes. There are wildlife refuges and national parks. Jordahl says he's deeply concerned about cutting these ecosystems in two.
JORDAHL: To think we could do something like this, free of significant environmental consequences, it's delusional. We're fundamentally changing the landscape here.
FALK: Fundamentally changing the landscape without the benefit of environmental reviews. Back in 2005, Congress gave the Department of Homeland Security the ability to waive a whole host of environmental laws in order to expedite building the wall. Jordahl's group and others have filed numerous lawsuits challenging those waivers. Most have failed. And now they've joined two other conservation groups in a new lawsuit against the national emergency declaration.
The Customs and Border Protection officials says the agency does conduct research and surveys before construction to, quote, "identify and avoid or mitigate potential impacts to sensitive locations" - end quote. Still, skeptics remain skeptical. Kevin Bixby is with the Southwest Environmental Center in Las Cruces, N.M.
KEVIN BIXBY: There's a lot of silly semantics going on in the national debate over whether it's a wall or fence. From our perspective, if it's a big structure that prevents the passage of wildlife, it's a wall.
FALK: Meanwhile, some experts have their eyes on the Rio Grande Valley, where new border fencing could cut through a flood plain. Josiah Heyman is at The University of Texas, El Paso.
JOSIAH HEYMAN: The fence wall is a huge barrier to the normal movement of water.
FALK: After a border wall was constructed in 2008 in parts of Arizona, monsoon floodwaters built up behind the wall and poured into the Mexican city of Nogales. Heyman says something similar could happen on both sides of the border in the Rio Grande Valley.
HEYMAN: We really do share the same water, and it's something that you can't build a wall through.
FALK: In the newly-signed border security bill, some ecological sites in South Texas were specifically protected, but it's not clear if they will remain that way now that President Trump has declared a national emergency. For NPR News, I'm Mallory Falk, in Santa Teresa.
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