Kent Mayo


Washington, D.C.

P: +1.202.639.1122 F: +1.202.585.1007
Kent Mayo Photo

Kent Mayo handles a wide variety of environmental matters, with a focus on environmental litigation and enforcement defense, permitting and regulatory compliance. His litigation work includes serving as lead counsel in multiple New Source Review and other actions brought by the United States, states and citizen groups. He also represents clients in toxic tort and class action litigation arising from environmental issues. In the regulatory sphere, Mr. Mayo counsels clients on permitting issues and has assisted clients in obtaining and defending permits issued for new facilities in multiple jurisdictions. Mr. Mayo is a member of the firm's global Climate Change Practice and counsels clients on climate change policy developments and potential impacts on business operations, including EPA rulemakings regarding permitting and standards for GHG emissions.

Mr. Mayo previously worked as a trial lawyer in the Environmental Enforcement Section of the U.S. Department of Justice, where he led teams in complex environmental litigation, settlement negotiations and mediations in a broad range of civil environmental actions, including cases involving Clean Water Act and Clean Air Act violations and cases arising under CERCLA's remedial, cost recovery and natural resource damages provisions.

Related Experience

Litigation and Enforcement Defense

  • Representation of water provider as national counsel defending class action litigation filed following chemical spill impacting water supplies
  • New Jersey v. RRI Energy Mid-Atlantic Power Holdings, LLC - Litigation counsel representing power producers in federal Clean Air Act citizen suit litigation in Pennsylvania
  • United States v. Louisiana Generating LLC - Lead litigation counsel representing power producer in defense and settlement of USDOJ Clean Air Act NSR lawsuit
  • WildEarth Guardians v. Public Service Company - Lead litigation counsel representing power producer in defense of Clean Air Act citizen suit alleging opacity violations
  • Representation of utility in negotiation of settlement of alleged NSR claims regarding sulfuric acid mist emissions
  • WildEarth Guardians v. Public Service Company - Litigation counsel defending power producer against Clean Air Act citizen suit alleging MACT violations; obtained favorable verdict in federal district court; dismissal upheld by Tenth Circuit Court of Appeals
  • United States v. Kentucky Utilities Company - Lead litigation counsel representing utility in defense and settlement of USDOJ Clean Air Act NSR and NSPS lawsuit
  • Sierra Club v. Dayton Power & Light - Litigation counsel for three co-owners of an Ohio power plant in defense and settlement of lawsuit alleging Clean Air Act violations
  • Representation of power producer in challenge to Title V permit by citizen groups in Tenth Circuit Court of Appeals
  • Representation of major engine manufacturer in dispute with United States regarding settlement compliance in federal district court and D.C. Circuit
  • Complex technical settlement with a municipal entity requiring substantial injunctive relief under the Clean Water Act arising from unpermitted sewer overflows
  • Clean Air Act settlement with a major petroleum refiner requiring injunctive relief and civil penalties with respect to five refineries, including court defense of the settlement against citizen challenges
  • Lead counsel on DOJ/EPA case team presented with the EPA National Superfund Enforcement “Team of the Year” Award for representation of the United States’ enforcement and defensive interests in a multiparty CERCLA action

Permitting and Compliance

  • Advise utilities on compliance with CCR rule and Clean Water Act ELGs
  • Representation of utility in defense to administrative challenges to construction permit issued for new coal-fired generating unit in Kentucky
  • Representation of power producer in permitting actions and administrative and state judicial permit challenges to construction permit for $1.3 billion coal-fired generating unit in Colorado
  • Assisted client in defending challenges to Title V permit and responding to EPA statements on issues of first impression regarding PM2.5 monitoring
  • Advise various clients on NSR and Title V compliance issues, as well as compliance with changing regulatory requirements under national regulatory programs including the EGU MACT, Boiler MACT, Clear Air Interstate Rule, Cross-State Air Pollution Rule, SSM Policy and greenhouse gas regulations


Publications, Speeches & Presentations