Deidre Duncan

Hunton Andrews Kurth LLP

A co-leader of the firm’s environmental practice, Deidre G. Duncan is lauded in Chambers USA, 2016 as “extremely capable,” “very familiar with the regulations and agencies,” and excels at giving clients “good insight into getting an expeditious outcome.” Her practice focuses exclusively on environmental, energy and administrative law.

Deidre represents clients on permitting, compliance and litigation relating to the Clean Water Act (CWA), the Endangered Species Act (ESA), the National Environmental Policy Act (NEPA) and other environmental statutes.

She frequently counsels clients on administrative rulemaking and policy, providing regulatory clarifications when necessary, and drafting federal and state legislation on myriad intricate issues.

She is also well known for negotiating and obtaining permits for complicated energy and development projects.

Her clients include development companies, oil and natural gas pipelines, electric utilities, agricultural interests, state and local agencies, and various trade associations.

Prior to entering private practice, Deidre served as assistant general counsel of the Army at the Pentagon, advising the secretary of the Army on environmental and land use issues involving the Corps of Engineers’ Civil Works and section 404 Regulatory program, as well as the Base Realignment and Closure (BRAC) program.

Deidre has extensive experience with federal regulatory agencies, military departments and the US Department of Justice.

Deidre is a contributor to the firm’s environmental blog, The Nickel Report, and the firm’s pipeline industry blog,


  • Advise several of the nation’s largest interstate natural gas pipelines on environmental permitting and siting matters, regulatory compliance, and litigation under the CWA, ESA, NEPA and other federal environmental laws.
  • Advise liquid natural gas and coal export developers on NEPA, ESA, and CWA permitting and regulatory approvals.
  • Advise electric utilities and other energy companies on permitting electric transmission and other structures across federal lands administered by the Bureau of Land Management (BLM), the National Park Service (NPS), the United States Forest Service (FS), the Fish & Wildlife Service (FWS), and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEM).
  • Serve as lead counsel to a broad coalition of industry and agricultural associations on matters involving legislative and regulatory changes to the CWA.
  • Counsels Florida mining company in navigating Clean Water Act section 404 permitting process and related federal requirements, such as the National Environmental Policy Act review and the Endangered Species Act section 7 consultation process, and defends permit in subsequent litigation.
  • Assists with obtaining CWA and Rivers and Harbors Act jurisdictional determinations for industrial sites.
  • Assisting a large oil and gas producer in obtaining US Army Corps of Engineers approval for channel closure at a refinery site.
  • Represented mineral rights owner in a challenge alleging APA, NEPA, ESA, and NPS regulation violations against a National Park Service approval of a three-dimensional seismic geophysical survey in a National Preserve.
  • Obtained CWA and other permits for a pipeline projects in Ohio, Michigan, Illinois, and Texas.
  • Advised an interstate natural gas pipeline company on ESA, the Marine Mammal Protection Act (MMPA), the CWA and US Coast Guard requirements with respect to an offshore LNG facility and pipeline.
  • Advised an interstate natural gas pipeline company on the interplay between BOEM and and Corps of Engineers’ regulations on abandonment of offshore pipelines.
    Advise major water utility on federal water supply authorities.
  • Counsel to one of the largest coal companies on precedential legal challenge to EPA veto authority under section 404(c) of the CWA.
  • Counsel to coalition challenging agency CWA guidance as violating the Administrative Procedure Act’s rulemaking requirements.
  • Obtained critical regulatory changes to streamline the Corps of Engineers’ section 404 permitting and NEPA compliance.
  • Expedited federal environmental permitting approvals for a 400-mile oil pipeline, successfully avoiding construction delays.
  • Represent land developers on jurisdictional determinations, use of general permits, expedited permitting procedures, and mitigation requirements under section 404 of the CWA.
  • Advised an interstate natural gas pipeline company in a potential enforcement action under the ESA; reached successful settlement with the FWS.
  • Lead counsel for a coalition of industry and agricultural interests on various CWA and ESA cases at the United States Supreme Court, including Rapanos v. United States.
  • Prepare comments on EPA and Corps rulemakings under the CWA and FWS and National Marine Fisheries Service (NMFS) under the ESA.
  • Advise state and local governments and private entities on Corps of Engineers’ real estate and water resources development project authorities.


  • JD, University of Cincinnati College of Law, Order of the Coif, 1996
  • BA, Duke University, cum laude, 1993


  • District of Columbia


  • General Counsel, Pentagon, United States Army
  • Captain, United States Army
  • Assistant to the General Counsel, United States Army
  • Extern, Federal District Court


  • Member, American Bar Association


Rate : $$$

What types of cases Attorney Deidre Duncan & Hunton Andrews Kurth LLP can handle?
Hunton Andrews Kurth LLP can handle cases related to laws concerning Real Estate, Litigation, Administrative, International Law, Transportation, Energy Utilities & Environmental. We manually verify each attorney’s practice areas before approving their profiles and reviews on our website.
Where is Hunton Andrews Kurth LLP located?
Hunton Andrews Kurth LLP is located at The Avenue, 2200 Pennsylvania Ave NW, Washington, DC 20052, USA. You can reach out to Hunton Andrews Kurth LLP using their phone line 202 955 1919. You can also check their website or email them at [email protected].
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