Stephanie Osler Hastings

Stephanie Osler Hastings



Specialized California water law expertise. Trusted strategic advisor and project manager for complex water supply and infrastructure projects. Innovative problem solver for high-stakes water disputes.

With more than 20 years of specialized expertise in water law, Stephanie Hastings has played a leading role in California’s most complex and precedent-setting water matters. She brings sophisticated legal skill and experience to the acquisition, maintenance and protection of water resources and rights. A skilled project manager, Stephanie excels at providing strategic advice for complex, dynamic and often novel water matters and thrives in high-stakes, multiparty transactions and litigation.

Stephanie represents wholesale and retail water providers, regulated utilities, government entities, agriculture and large landowners, investment funds, energy and land developers, and recreational resorts, among others. Clients value her attention to detail and deft judgement when navigating the myriad challenges inherent in advancing projects in a water-scarce environment.

Her practice spans every aspect of water law, including the development, maintenance and protection of water rights, securing utility services for land development, complex water rights litigation, marketing of supply and rights through transfers and exchanges, development of supplemental supplies including imported and recycled water supplies, reorganization of utility enterprises, and regulatory and environmental compliance for water supply operations and infrastructure projects.

As a director of The Aquaya Institute, Stephanie is dedicated to advancing global health through universal access to safe water. She is also a co-founder of the California H2O Women Conference—empowering and inspiring women to improve the way we manage California’s and the world’s most valuable and vital natural resource.

Representative Matters

Water Rights - Strategy, Maintenance, Protection and Development

  • Special water rights counsel to California municipal water providers. Representation includes advising electeds, city attorneys and utility managers on water supply and rights matters; maintenance, protection and development of real property and contractual rights to surface, groundwater, imported water, recycled water and stormwater supplies; regulatory and environmental compliance associated with the development, treatment and delivery of water supplies and infrastructure; and representation in litigation.

  • Special water rights counsel to a municipal water provider on all water rights matters associated with the proposed annexation of the city’s water and wastewater systems by a neighboring water district, including negotiation and drafting of a series of one-of-a-kind agreements that transfer an entire portfolio of water rights, including numerous historic and senior priority rights.

  • Water rights counsel to The Wonderful Company, a multi-billion dollar agriculture company, in complex groundwater litigation and the maintenance and protection of the company’s water rights in high priority groundwater basins throughout California in the context of the implementation of the Sustainable Groundwater Management Act.

  • Counsel to the Central Coast Water Authority, a joint powers authority comprised of eight public agencies, that delivers imported State Water Project water to  water providers and end users serving more than 80% of Santa Barbara County and also contracting parties in San Luis Obispo County. The Authority also  owns and operates the delivery and treatment facilities that make State Water Project water available to California’s central coast. Brownstein advises the Board and staff on public agency matters, including compliance with open meeting, state and Federal laws, the Public Records Act, CEQA, conflicts. Brownstein represents the Authority in public agency meetings, transactions with the California Department of Water Resources and the County regarding the implementation of a long-term water supply contract, as a member of the State Water Contractors, and in litigation.

Regulatory and Environmental Compliance

  • On behalf of two major municipal water suppliers, obtained regulatory approvals of the cities’ respective recycled water projects, including reductions in the cities’ respective discharges of highly treated wastewater to the Los Angeles River, and overcame project opposition. Representation included successfully settling litigation challenging one of the city’s compliance with CEQA for its recycled water project in a manner that allowed the City’s project to be implemented.

  • On behalf of a national homebuilder, obtained approval of the Water Supply Assessment (SB 610) for development of a 1,500 acre-property in California proposed to include 5,400 residential units and commercial uses. The water supply included imported water, surface water, groundwater, stormwater and recycled water supplies over a 30-year build-out and raised numerous water issues, including the production of groundwater from adjudicated and non-adjudicated basins, groundwater storage, conjunctive use, the delivery and use of imported State Water Project supplies, water re-use, flood protection and stormwater management.

  • Successfully defended a landowner's surface water diversions, including negotiation of a settlement with the California Department of Fish and Wildlife and the National Marine Fisheries Service regarding violations of the state and federal Endangered Species Acts.

  • Counsel to one of California's largest wholesale water suppliers with respect to its compliance with the federal and state Endangered Species Acts for water supply and flood control operations in four major watersheds draining to the San Francisco Bay. Included the development of a 50-year, multispecies habitat conservation plan and associated implementation agreement and CEQA and NEPA documents; acquisition of NMFS, USFWS and the CDFG (now the CDFW) incidental take permits for approximately 25 covered terrestrial and aquatic species; and implementation of a multi-agency settlement of a water rights complaint alleging violations of the public trust and CDFG Section 5937, including the State Water Resources Control Board's approval.


  • Lead counsel in litigation brought by a joint powers agency and its eight member agencies against a county agency for actions that impair the rights of the plaintiff agencies to transfer and exchange their imported State Water project supplies.

  • Representation of the Cities of Burbank and Glendale in four consolidated trial court proceedings challenging regulatory approvals issued by the Regional and State Water Boards to the four publicly owned treatment facilities that discharge highly treated wastewater to the Los Angeles River. Continued representation of Burbank in its appeal of the trial court’s decision granting a writ of mandates and overturning the City’s waste discharge requirements.

  • On behalf of an association of retail water providers in the West and Central groundwater basins, successfully obtained reversal in full of two related trial court decisions denying motions to amend judgments governing the basins, which provide local water supplies to the millions of people living and working in the greater Los Angeles region. The motions had sought to provide for the conjunctive use and management of the basins, including procedures for use of the basins' available storage space.

  • Successfully defended and settled complex and high stakes water rights litigation that threatened to enjoin a municipality’s groundwater production and operation of a $30 million treatment facility, which in turn would have forced the client to rely entirely on costly and less reliable imported supplies. The settlement implements a physical solution that protects the client’s water rights, permits continued operation of its facilities and substantially reduces litigation risk.

Insights & Publications



  • J.D., University of California, Hastings College of Law
  • B.A., University of Vermont
  • St. Paul’s School, Concord, New Hampshire


  • California
  • U.S. District Court, Central District of California
  • U.S. Court of Appeals, Ninth Circuit

Membership & Community

Director, The Aquaya Institute (2011-present)

Director, California Groundwater Resources Association (2004-2009)

Member, State Water Contractors, Legal Affairs Committee

Member, Groundwater Resources Association

Member, The Association of Women in Water, Energy, Environment

Member, Association of California Water Agencies



Best Lawyers in America, 2020-2024

Who’s Who in Energy & Environment, Pacific Coast Business Times, 2019

Who's Who in Professional Services, Pacific Coast Business Times, 2018

Best Lawyers in America, 2018-2020

Co-Chair, Natural Resources Department, 2009-12

Top Women in Business, Pacific Coast Business Times, 2012

Chambers USA, America’s Leading Business Lawyers, Environmental Law, 2009-2010

Top 40 Under 40, Pacific Coast Business Times, 2009

Water Practice Group Leader, 2005-09