Duncan has more than 25 years of experience in environmental regulatory law in Texas. He focuses his practice on representing businesses and governmental subdivisions in permitting, enforcement, and rulemaking issues before the Texas Commission on Environmental Quality (“TCEQ”) and the Environmental Protection Agency.

Prior to joining Lloyd Gosselink, Duncan was the General Counsel to the TCEQ, providing legal advice and counsel to the three Commissioners appointed by the Governor on permitting, enforcement and rulemaking matters. He also managed the TCEQ’s litigation.

Duncan is a former Administrative Law Judge for the Texas Water Commission, a Fellow at the U.T. School of Law Center for Public Policy Dispute Resolution, and is a guest lecturer at the U.T. School of Law.


  • Practice Areasopen

  • Educationopen


    • J.D., Texas Tech University School of Law (1984)
    • B.B.A., Texas Tech University (1981)


  • Professional Licensesopen


    • Admitted to State Bar of Texas (1985)


  • Representative Experienceopen


    • Permitting of largest landfill expansion in Texas
    • Permitting Greenfield sites for new landfills
    • Successfully defending numerous clients in TCEQ environmental enforcement matters
    • Negotiating Agreements with opposing parties and local governments on environmental issues
    • Air Quality Permitting of rock crushers and frac sand processers
    • Successfully advocating for TCEQ rule amendments
    • Assisting clients with Texas Risk Reduction Program remediations
    • Assisting clients with TCEQ Voluntary Clean-up Program approvals
    • Assisting clients with municipal setting designations
    • Advising clients on waste management matters

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  • Publications & Presentationsopen


    • Texas Tech School of Law, “TCEQ Enforcement Process”
    • TWCA Water Law Conference, “TCEQ Enforcement of Edwards Aquifer Rules”
    • U.T. Water Law Seminar, “Water Reuse”
    • Advanced Administrative Law Conference, “Rulemaking Issues”
    • Texas Aggregate and Concrete Association Conference, “TCEQ Permit Process


  • Professional Associations & Membershipsopen


    • Board Certified in Administrative Law by the Texas Board of Legal Specialization
    • State Bar of Texas
    • Austin Bar Association, Environmental Law Section
    • American Bar Association


  • Personal Profileopen


    Duncan and his wife, Jo Betsy have two sons in college: Reed, a Red Raider and Cole, a Longhorn. An avid sports fan, Duncan coached his sons in youth league and AAU basketball for 15 years. He still plays basketball and enjoys golf. Duncan and Jo Betsy enjoy playing fetch and swimming with their two dogs Daisy, a yellow lab and Dottie, a Jack Russell terrier.