The federal government is replacing barriers between Arizona’s Organ Pipe Cactus National Monument, right, and Sonyota, Mexico. The barriers there now are meant to stop cars from crossing the border. The new ones are meant to stop people traveling on foot. Environmentalists say the new barriers will harm wildlife. (Matt York/AP)

The U.S. government plans on replacing barriers through 100 miles of the southern border in California and Arizona through a national monument and a wildlife refuge, according to documents and environmental advocates.

Barriers meant to stop people from crossing the border on foot will go up at Organ Pipe Cactus National Monument, a vast park named after the unique cactus breed that decorates it. The barriers will also run through Cabeza Prieta National Wildlife Refuge, which is a designated wilderness home to 275 wildlife species. The government will also build new roads and lighting in those areas of Arizona.

The Department of Homeland Security on Tuesday again rejected environmental and dozens of other laws to build more barriers along the U.S.-Mexico border.

Environmental advocates who have sued to stop the construction of a border wall say this plan will hurt the wildlife in those areas.

“The Trump administration just ignored bedrock environmental and public health laws to plow a disastrous border wall through protected, spectacular wild lands,” said Laiken Jordahl, who works on border issues at the Center for Biological Diversity.

Funding will come from the Defense Department following the emergency declaration that President Trump signed this year after Congress refused to approve the amount of border-wall funding he requested.

The Department of Homeland Security did not immediately respond to a request for comment.

At Organ Pipe, row after row of cactuses decorate 516 square miles of land that once saw so much drug smuggling that more than half the park was closed to the public. But drug-related crossings in that area dropped off significantly, and the government in 2015 reopened the entire monument for the first time in 12 years.

The government has already demolished refuge land in the Rio Grande Valley of Texas and wall construction is set to begin any day. In one section of the Lower Rio Grande Valley National Wildlife Refuge, crews have used heavy construction equipment to destroy a mix of trees, including mesquite, mulberry and hackberry. Those trees protect birds during the ongoing nesting season.

In Arizona, construction will focus on four areas of the border and will include the replacement of waist-high fencing meant to stop cars with 18- to 30-foot barriers that will be more efficient at stopping illegal crossings. The Center for Biological Diversity says the plans total about 100 miles of southern border in both Arizona and California, near Calexico and Tecate.