An East Bay congressman reacted angrily Friday to a report that the U.S. Navy is reviewing plans to potentially build large-scale detention centers for undocumented immigrants in various parts of the country, including Concord.

Time magazine detailed what was described as a draft memo that was submitted for approval by Secretary of the Navy Richard Spencer, outlining plans to build temporary tent cities to house thousands of immigrants in the south as well as up to 47,000 people at the former Naval Weapons Station in Concord.

Time did not publish the memo, and Navy officials would not comment. “It would be inappropriate to discuss internal deliberative planning documents,” said Capt. Gregory Hicks, an agency spokesman.

The Trump administration in early May instituted a “zero-tolerance” policy for those who illegally cross the border to the U.S., leading to an influx of immigrants charged in criminal court and, as a result, more than 2,300 children separated from their parents.

President Trump signed an executive order this week calling for detaining families together, though a judge must decide whether that squares with a legal case that ensures children are not held indefinitely.

According to the Time report, the planning document “suggests these tent cities be built to last between six months and one year.”

Johnny Michael, a spokesman for the Department of Defense, said agency officials are “conducting prudent planning and are looking at all available regions should DHS ask for assistance in housing adult illegal immigrants. At this time there has been no request” from the Department of Homeland Security.

In response to the report, Rep. Mark DeSaulnier, D-Concord, said the Trump administration “needs to take a time out.”

“This is no way to effectuate intelligent immigration policy, including for those seeking asylum. This is absolute madness and I oppose it wholeheartedly,” DeSaulnier said in a statement. “If the Administration wants to have a rational dialogue about fixing our immigration system, I am happy to do that, but making up immigration policy on the fly is just wrong. We will fight this in every way we can.”

A news release from the city of Concord said the city is concerned to hear the reports, but that it had not heard directly from the Navy about the issue. The release said the city does not have jurisdiction over the site.

The Concord Naval Weapons Station is home to one of the largest redevelopment projects in the Bay Area, a scheme that rivals San Francisco’s Hunters Point Shipyard project in size and ambition. The current proposal calls for building up to 12,200 housing units and 6.1 million square feet of commercial space on about 2,300 acres of the former military base.

In addition, the East Bay Regional Park District will receive 2,600 acres for what will become the Concord Hills Regional Park. The Navy is scheduled to begin transferring land to the city in late 2018.

The developer of the project is Lennar. FivePoint, a spin-off of Lennar, is managing the development process. The same team is redeveloping the former shipyard in San Francisco. Negotiations between Concord and the developer are ongoing.

The current plan calls for a 500-acre phase one, which would include 4,392 housing units, 1.7 million square feet of commercial space, two community centers, a new school and 79 acres of parks and open space.

Hamed Aleaziz and J.K. Dineen are San Francisco Chronicle staff writers. Email: haleaziz@sfchronicle.com, jdineen@sfchronicle.com Twitter: @haleaziz @sfjkdineen