The $2.1 million pilot project is due to begin this week. If successful, it could be expanded along up to 130 miles of river in the patrol's Laredo Sector, as well as other parts of the U.S.-Mexico border.
Critics say the action is similar to the Vietnam War-era Agent Orange chemical program and worry that it could be harmful over the long term. Opponents are also concerned that the spraying will occur near the cities of Laredo and Nuevo Laredo, Mexico.
"We don't believe that is even moral," said Jay Johnson-Castro Sr., executive director of the Rio Grande International Study Center, located at Laredo Community College, adjacent to the planned test area. "It is unprecedented that they'd do it in a populated area."
The Border Patrol and U.S. Environmental Protection Agency officials say the chemical is safe for animals. The program is designed to keep border patrol agents safe and help make their jobs easier.
"We are trying to improve our mobility and visibility up and down the river," said Border Patrol agent Roque Sarinana.
But the program still has many detractors.
Members of the Laredo City Council have raised concerns about the spraying program and called on Mexico President Felipe Calderon to intervene. And Mexican officials are worried that the herbicide - called Imazapyr - could threaten the Nuevo Laredo water supply.
Imazapyr was registered in the United States in 1984. The EPA concluded in tests that "there is a reasonable certainty that no harm will result to the general population, and to infants and children from aggregate exposure to imazapyr residues."
A U.S. government outline of the project indicates the Border Patrol is going to test three methods to rid the 1.1-mile bank of river of carrizo cane, which has thick stalks that form tight, isolated trails that can be dark and all but invisible from higher up on the bank.
One method calls for the cane to be cut by hand and the stumps painted with the herbicide. Another involves using mechanical equipment to dig the cane out by the roots, possibly without the need for the herbicide.
The third and most controversial removal method calls for helicopters to spray Imazapyr directly on the cane, until all plant life in the area is poisoned.
The Border Patrol said that after using the herbicide, it plans to make the river's edges green again by planting native plants.
The cane is a non-native plant introduced by Spanish explorers centuries ago. Johnson-Castro said he has no issue with removing the cane, just the method of getting it done.
Laredo Mayor Raul Salinas said he believes federal officials when they say testing shows the chemical is not dangerous. But he also realizes opponents have concerns to evaluate.
"It is a complicated situation because we have to think about protecting our border," said Salinas, a retired FBI agent. "But let's do it in a sensible, reasonable way to make sure humans won't be harmed, nor the vegetation, nor the animals, nor the environment."
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