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With more than twenty years of experience in federal, state, and local air quality laws and in representing clients across the U.S. from a variety of industries, Bill is uniquely skilled at providing effective counsel and working toward solutions that best serve his client’s specific needs.  Bill is dedicated to helping clients understand their compliance obligations under the myriad of air quality programs, regulations, and agency guidance so that such obligations can be managed as effectively and efficiently as possible.  Given the multi-disciplinary nature of air quality matters, Bill often serves as a catalyst for creating a team approach to problem solving by working closely with management, technical and operational personnel, consultants, and regulators to achieve favorable results for his clients.


A hallmark of Bill’s practice is assisting clients obtain air quality permits or permit revisions to authorize new facilities or changes at existing facilities in a timely manner.  Bill helps clients identify applicable requirements, prepare applications, and negotiate with permitting authorities to establish permit terms that clearly and accurately reflect underlying legal obligations, impose conditions that are least burdensome as possible, and provide necessary operational flexibility.  He also regularly assists clients in developing systems that ensure compliance after permit issuance, as well as with the preparation of compliance certification, monitoring, and other reports required by the permit.


While Bill counsels clients to take a proactive approach to air quality regulatory compliance, even the most well-managed facilities can experience problems.  When problems occur, Bill counsels clients in taking appropriate corrective action and providing applicable notifications to regulators.  Moreover, Bill has substantial experience assisting clients in responding to agency requests for information, notices of violations, and enforcement actions. With his keen insight, Bill has helped clients successfully resolve compliance issues and, when necessary, negotiate orders or other settlement agreements with enforcement authorities.



  • ENVIRONMENTAL - Environmental Assessment, Environmental Counseling, Environmental Natural Resources, Environmental Regulatory Enforcement, Environmental Regulatory Permitting, Environmental Rulemaking
  • NATURAL RESOURCES - Air Quality, Oil & Gas
  • ENVIRONMENTAL, SOCIAL & GOVERNANCE (ESG) - Environmental, Social License & Community Relations



  • Arizona, 1997
  • Texas (pending)
  • U.S. District Court, District of Arizona, 1997
  • U.S. Court of Appeals, Ninth Circuit, 1998



  • State Bar of Arizona, Member
  • State Bar of Arizona, Environmental and Natural Resources Law Section, Member
  • Maricopa County Bar Association, Environmental and Natural Resources Law Section, Member
  • Arizona State University, Center for Environmental Studies, Past Adjunct Faculty
  • Arizona Chamber of Commerce and Industry, Air Quality Subcommittee, Member
  • Arizona Mining Association, Air Quality Subcommittee, Member



  • America's Top 50 Lawyers - Environmental Law - Arizona - 2023
  • Best Lawyers in America®, Environmental Law, 2024; Natural Resources Law, 2023-2024



Contact info:

  • (602) 530-8125



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William C. B. Underwood - America's Top 50 Lawyers - Environmental Law - Arizona

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