The Joe Biden White House announced it waived 26 federal laws in south Texas to allow border wall construction on Wednesday, marking the administration’s first use of a sweeping executive power employed often during Donald Trump’s presidency.

Homeland security department officials posted the announcement on the US federal registry with few details outlining the construction in Starr county, Texas, which is part of a busy border patrol sector seeing “high illegal entry”. According to government data, about 245,000 illegal entries have been recorded so far this fiscal year in the Rio Grande Valley sector, which contains 21 counties.

“There is presently an acute and immediate need to construct physical barriers and roads in the vicinity of the border of the United States in order to prevent unlawful entries into the United States in the project areas,” the homeland security secretary, Alejandro Mayorkas, stated in the notice.

The Clean Air Act, Safe Drinking Water Act and Endangered Species Act were some of the federal laws waived by the Department of Homeland Security (DHS) to make way for construction that will use funds from a congressional appropriation in 2019 for border wall construction. The waivers avoid time-consuming reviews and lawsuits challenging violation of environmental laws.

Starr county’s hilly ranchlands, sitting between Zapata and McAllen, Texas, is home to about 65,000 residents sparsely populating roughly 1,200 square miles (3,108 sq km) that form part of the Lower Rio Grande Valley National Wildlife Refuge.

Although no maps were provided in the announcement, federal customs and border protection officials announced the project in June and began gathering public comments in August when they shared a map of the additional construction that can add up to 20 miles (32km) to the existing border barrier system in the area. The Starr county judge Eloy Vera said it will start south of the Falcon Dam and go past Salineño, Texas.

“The other concern that we have is that area is highly erosive. There’s a lot of arroyos,” the county judge said, pointing out the creeks cutting through the ranchland and leading into the river.

Concern is shared with environmental advocates who say structures will run through public lands, habitats of endangered plants and species like the ocelot, a spotted wild cat.

“A plan to build a wall through will bulldoze an impermeable barrier straight through the heart of that habitat,” Laiken Jordahl, a south-west conservation advocate for the Center for Biological Diversity, said on Wednesday afternoon. “It will stop wildlife migrations dead in their tracks. It will destroy a huge amount of wildlife refuge land. And it’s a horrific step backwards for the borderlands.”

During the Trump administration, about 450 miles (724km) of barriers were built along the south-west border between 2017 and January 2021. The governor of Texas, Greg Abbott, renewed those efforts after the Biden administration halted them at the start of his presidency.

Wednesday’s decision contrasts the Biden administration’s posturing when a proclamation to end the construction on 20 January 2021 stated: “Building a massive wall that spans the entire southern border is not a serious policy solution.”

In a statement on Wednesday, border officials said the project is consistent with that 2021 proclamation. “Congress appropriated fiscal year 2019 funds for the construction of border barrier in the Rio Grande Valley, and [homeland security] is required to use those funds for their appropriated purpose,” the statement said.

The statement said officials were “committed to protecting the nation’s cultural and natural resources and will implement sound environmental practices as part of the project covered by this waiver”.

The announcement prompted political debate by the Democratic administration facing an increase of migrants entering through the southern border in recent months, including thousands who entered the US through Eagle Pass at the end of September.

“A border wall is a 14th-century solution to a 21st-century problem,” the Texas congressman Henry Cuellar said in a statement. The Democrat added: “It will not bolster border security in Starr county.

“I continue to stand against the wasteful spending of taxpayer dollars on an ineffective border wall.”