Clarissa Howley Mills

Clarissa Howley Mills is a partner in the Environmental Practice Group in Haynes Boone’s Dallas office.

Her practice focuses on environmental matters, including regulatory and enforcement. Clarissa joined the firm after nearly a decade with the United States Environmental Protection Agency (EPA), most recently as Deputy Regional Counsel for EPA Region 6. As Deputy, she managed one of the largest regional attorney offices and provided strategic counsel on permitting, state oversight, and high-stakes enforcement matters in the five-state region.

Clarissa has significant experience advising on matters in key environmental statutes such as the Clean Air Act, Clean Water Act, RCRA, and Superfund, and multiple other acts and regulations. During her time as the lead senior counsel for chemical enforcement actions, Clarissa served as a national expert in investigating industrial accidents under the Chemical Accident Prevention regulations, securing settlements totaling tens of millions of dollars in penalties and extensive environmental compliance measures.

Clarissa has handled a broad array of environmental matters while at the EPA from pesticides under the Federal Insecticide Fungicide and Rodenticide Act to underground injection control (UIC) permitting under the Safe Drinking Water Act and National Historic Preservation Act. She frequently managed complex multi-statute matters that required regulatory coordination with other federal and state regulators including with the Department of Justice (DOJ), Occupational Safety and Health Administration (OSHA), U.S. Department of Energy (DOE), the Texas Commission on Environmental Quality (TCEQ), and the Texas Railroad Commission, among others.

During her time at EPA, she led and oversaw permitting and enforcement efforts in environmental regulations across various sectors, from petrochemical plants and hazardous waste management to Superfund and Clean Water Act cases. Clarissa spent a substantial amount of time guiding agency permitting and enforcement efforts and has unique insights into the agency’s processes.

Drawing on her extensive institutional knowledge and agency insight, Clarissa is well suited to assist clients in tackling their most challenging environmental issues. Clarissa’s background in agriculture provides her with an understanding of the importance of sustainable business practices, fostering a strong work ethic and the ability to approach challenges with practical solutions.