Construction was scheduled to begin August 22, but is now slated to begin in early October or later for most of the wall. Building in just one section, a two-mile segment in the state, will proceed as planned, beginning on August 19, according to that court filing.
On August 6, the Tucson-based Center for Biological Diversity filed a preliminary injunction in U.S. District Court in Washington, D.C., asking a judge to halt construction in Arizona.
In July, the Center, along with two other activist groups, challenged the administration's decision to waive more than 40 protective laws in order to build new walls in California and Arizona. They requested the injunction in Arizona until a judge rules in that case.
"The change in construction schedule just gives everybody a temporary sigh of relief," Jean Su, an attorney for the Center for Biological Diversity, told Phoenix New Times.
Why the administration decided to wait is unclear. "We don't know what happened," Su said.
A spokespeople for the Department of Homeland Security deferred to the Department of Defense, which is funding the proposed new wall in Arizona.
A spokesperson for the Department of Defense did not immediately respond to a request for comment.
Emails between Su and the Department of Justice, submitted as an exhibit in the July challenge, show that the administration expected construction to begin "around August 21."
In its opposition brief to the Center's requested injunction, the administration requested that the judge deny the motion.
The brief also spelled out when the administration expected to begin building different sections of the wall.
Although miles of pedestrian barriers of double-wire mesh and vehicle barriers already split Arizona and Mexico, the administration wants to replace both with 30-foot bollard walls, which are thick steel posts filled with concrete.
Construction on the two-mile section near the Lukeville port in Organ Pipe Cactus National Monument would begin August 19 and take 45 days to build, the administration estimated in filings Tuesday.
After that section was done, construction on 38.6 miles of wall in other parts of the monument and in the Cabeza Prieta National Wildlife Refugee would begin in "early October," it said.
As for plans to build a bollard wall through the San Pedro Riparian National Conservation Area, by "filling the gap in existing fencing around the San Pedro River," construction would not begin "until early October or after."
"DHS plans to conduct geotechnical surveys in and around the riverbed in mid-to-late September, which will be prerequisite to finalization of the contract and designs," it said.
In a declaration filed with the court, Paul Enriquez, DHS's director of acquisitions, real estate and environment for the border wall program, said that "[the Department of Defense] expects to conduct no other removal of existing barriers or construction of bollard wall in the Challenged Project Areas before October 1, 2019."
The Department, which is funding these highly controversial sections of border wall, estimated that the construction would be finished in January 2021, Enriquez added.
Su, with the Center for Biological Diversity, remained hopeful that the Center's July challenge would succeed.
"We're hopeful that the judge will see that the underlying waiver is unconstitutional," she said. If the judge agrees with the Center, the proposed border wall would have to go through environmental compliance processes and other reviews before it can be built.