Heather Welles


Thank you for your interest. Before you communicate with one of our attorneys, please note: Any comments our attorneys share with you are general information and not legal advice. No attorney-client relationship will exist between you or your business and O’Melveny or any of its attorneys unless conflicts have been cleared, our management has given its approval, and an engagement letter has been signed. Meanwhile, you agree: we have no duty to advise you or provide you with legal assistance; you will not divulge any confidences or send any confidential or sensitive information to our attorneys (we are not in a position to keep it confidential and might be required to convey it to our clients); and, you may not use this contact to attempt to disqualify O’Melveny from representing other clients adverse to you or your business. By clicking "accept" you acknowledge receipt and agree to all of the terms of this paragraph and our Disclaimer.


Heather Welles focuses her practice on complex litigation and appeals, with a particular focus on water and public law issues. She also has substantial experience representing entertainment-industry clients in a variety of disputes. Heather’s briefs have repeatedly carried the day in federal and state trial and appellate courts and arbitrations, including merits, certiorari, and amicus briefing at the US Supreme Court. She has briefed subjects including federal constitutional law, federal courts and jurisdictional issues, statutory interpretation, water law, land use, contracts, administrative law, and trademark law. Heather is a core member of the firm’s water practice, representing clients in areas including public agencies, agriculture, energy, private equity, and environmental conservation. She regularly speaks on water issues, including guest lecturing at Harvard, NYU, and UCLA law schools. Heather also maintains an active pro bono practice focused on civil rights and impact litigation.

In 2022, the Daily Journal recognized Heather as one of the forty top lawyers under the age of 40 in California, highlighting her water work and appellate practice.

Prior to joining O’Melveny, Heather served as a law clerk for the Honorable David S. Tatel on the DC Circuit Court of Appeals and the Honorable William A. Fletcher on the Ninth Circuit Court of Appeals.


Honors & Awards

  • Recognized by the Daily Journal's 2022, "Top 40 Under 40"
  • Member of the team recognized as Environment/Natural Resources Litigation Firm of the Year by Benchmark Litigation California (2019)


Bar Admissions

  • California

Court Admissions

  • US Supreme Court
  • US Court of Appeals, Ninth Circuit
  • US District Court, Central District of California


  • University of California at Berkeley, J.D.: Thelen Marrin Prize for Academic Excellence (best academic record in graduating class); Order of the Coif; Editor in Chief, Ecology Law Quarterly; Landis Prize (most accomplished research paper in water or local government law); American Jurisprudence Awards for best exam in Constitutional Law, Contracts, Water Law, and Land Use Law
  • University of California at San Diego, B.A., Political Science 

Professional Activities


  • Honorable David S. Tatel, US Court of Appeals, District of Columbia Circuit
  • Honorable William A. Fletcher, US Court of Appeals, Ninth Circuit


  • “Toward a Management Doctrine for Texas Groundwater,” Ecology Law Quarterly, Vol. 40 (2013)
  • “What’s a Smelt Worth?: The Endangered Species Act and the Commerce Clause in the Bay-Delta,” Ecology Law Quarterly, Vol. 39 (2012)
  • “Will the Wilderness Act Be Diluted in Drakes Estero?” Ecology Law Quarterly Currents (Aug. 26, 2012) (co-authored with Nell Green Nylen, Elisabeth Long, Mary Loum, Dan Carlin, Brynn Cook, and Sage Adams)

Representative Water and Natural Resources Matters

  • Agua Caliente Band of Cahuilla Indians v. Coachella Valley Water District. Representing Coachella Valley Water District in federal court on multiple matters of first impression involving reserved water rights, including successfully obtaining dismissal of several claims on standing grounds at summary judgment.
  • Las Posas Water Rights Coalition v. Fox Canyon Groundwater Management Agency & OPV Coalition v. Fox Canyon Groundwater Management Agency. Representing coalitions of large landowners in the first comprehensive groundwater adjudications under California’s new statutory adjudication scheme.
  • Advising on water rights and legal issues affecting water supply in multiple contexts, including disputes, major transactions, project development, governance, and regulatory compliance. Representative projects include multi-million-dollar transactions related to land and water rights acquisition and infrastructure development.
  • Represented a nonprofit organization in connection with high-profile negotiations over water quality in the Sacramento/San Joaquin River Delta system.

Representative Appellate Matters

  • City of Austin v. Reagan National Advertising of Texas Inc. Successfully represented the City of Austin at the US Supreme Court in a First Amendment dispute over billboard regulations, including obtaining certiorari and a favorable decision on the merits reversing the Fifth Circuit.
  • Padilla Ortiz v. Garland. Briefed and secured a rare victory on the papers at the Ninth Circuit in an immigration case, obtaining relief for a young woman seeking asylum.
  • Shoop v. Twyford. Primary author of amicus brief representing federal courts scholars in a habeas corpus case involving an order for medical testing issued under the All Writs Act.
  • Bostock v. Clayton County. Co-authored amicus brief on behalf of anti-violence organizations before the US Supreme Court defending a Sixth Circuit decision holding that transgender Americans are protected by Title VII’s prohibition on discrimination on the basis of sex.  The Supreme Court upheld the Sixth Circuit’s decision, and reversed a contrary decision by the Eleventh Circuit, by a 6-3 vote.
  • 11 Lagunita, LLC v. California Coastal Commission. Primary author of appellate briefing in a California Court of Appeal case involving administrative res judicata and Coastal Commission enforcement authority.
  • California Resources Corp. v. County of Monterey. Primary author of appellate briefing successfully defending a challenge to a local initiative impacting property rights and water use. Also obtained rare regulatory takings victory at bench trial as the primary brief drafter for the trial team and presented argument at trial and in collateral administrative proceedings.

Representative Litigation and Counseling Matters

  • Representing Warner Bros. in several important matters, including multiple contract disputes, litigation over financing participation rights, and counseling on COVID-19-related issues.
  • Served as the primary brief writer for a successful trial team defending a renowned dermatologist and his company in a contract and trademark dispute involving claims exceeding $80 million.
  • Served as the primary brief writer in a contract dispute defending a renowned boxer and his promoter.
  • Represented Planned Parenthood Arizona and individual clinicians in litigation challenging statutes that reduce access to reproductive health care.