Colorado Department of Public Health & Environment, Hazardous Materials & Waste Management Division v. United States

EBEL, Circuit Judge.

Since the 1950s, the United States has stored chemical weapons at the Army’s weapons depot located near Pueblo, Colorado (“Depot”). Congress has now mandated that the Army destroy those weapons by 2017. Separately, Congress authorized the State of Colorado to regulate hazardous waste in that state. Invoking that regulatory authority, Plaintiff-Appellant Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division (“Colorado” or “CDPHE”), has declared the chemical weapons stored at the Depot awaiting destruction to be hazardous…