ROXBURY, NJ — Federal officials say a proposed immigration detention center in Roxbury would house about 542 detainees, far below estimates cited by opponents, pushing back on claims of large-scale environmental and community impacts. In a legal brief filed April 23, attorneys for U.S. Immigration and Customs Enforcement (ICE) and the U.S. Department of Homeland Security (DHS) urged a federal judge to deny a request by the state and Roxbury to halt the project at 1879 Route 46 in Ledgewood.