(January 31, 2024, 11:42 AM EST) -- DENVER — The Center for Biological Diversity (CBD) has filed its opening brief in the 10th Circuit U.S. Court of Appeals in a direct appeal under the Clean Air Act (CAA) related to Colorado’s state implementation plan (SIP) for keeping air pollutants below the National Ambient Air Quality Standards (NAAQS), arguing that the U.S. Environmental Protection Agency violated the law in approving the plan. The SIP has particular application with regard to emissions associated with hydraulic fracturing activity....