Colorado Attorney General Phil Weiser has escalated a massive conflict over a shuttered state prison, filing a lawsuit against the federal government to block the facility from reopening as a new U.S. Immigration and Customs Enforcement detention center. The legal complaint targets the Department of Homeland Security and ICE, along with its leadership, asserting that federal agencies improperly bypassed mandatory environmental reviews before executing a lucrative contract to operate the facility. The prison, located about 30 miles northeast of Denver along Interstate 76, has sat vacant since October 2013.

The lawsuit asks a federal judge to throw out the five-year, $528.7 million contract that the government signed with the private prison operator GEO Group. The massive contract aims to operate the nearly 1,200-bed facility as the newly christened Big Horn immigration detention center. The state argues that ICE and DHS skipped the vital environmental review that is strictly required under the National Environmental Policy Act (NEPA). Weiser emphasized during a recent news conference that a facility shuttered for over a decade cannot simply be put back into heavy use without undergoing the legally required reviews.

The state’s lawsuit details significant environmental and infrastructural concerns regarding the proposed operations. Advocacy groups like GreenLatinos and the Colorado Immigrant Rights Coalition have also filed a parallel lawsuit alleging that ICE failed to assess air, water, and infectious disease impacts associated with reopening the long-vacant prison. Despite the legal challenges, the Attorney General has stated he believes the center could be on track to open by the end of the year if judicial intervention is not successful.

The Department of Homeland Security has pushed back aggressively against the state’s legal maneuvers. In a pointed statement, the agency claimed the lawsuit is not genuinely about environmental protection, but rather a political effort to stop President Trump’s immigration policies, accusing critics of ignoring environmental damage caused during previous administrations.

This federal litigation compounds existing legal troubles for the facility’s operators. Earlier this year, the immigrant rights advocacy group Together Colorado filed a separate lawsuit in state court, arguing that the property lacks the proper zoning for a detention center. That lawsuit accuses the town of Hudson of ignoring its own land use codes by allowing the GEO Group to commence renovations without acquiring a special use permit. Between the state and federal lawsuits, officials have requested that the federal contract be vacated and all ongoing renovations be immediately halted.