National Audubon Society v. Superior Court (Supreme Court of California, 1983, ) was a key case in California highlighting the conflict between the public trust doctrine and appropriative water rights. The Public Trust Doctrine is based on the principle that certain resources (such as navigable waters) are too valuable to be privately owned and must remain available for public use. In National Audubon Society v. Superior Court, the court held that the public trust doctrine restricts the amount of water that can be withdrawn from navigable waterways. The basis for the Public Trust Doctrine goes back to Roman law. Under Roman law, the air, the rivers, the sea and the seashore were incapable of private ownership; they were dedicated to the use of the public. In essence, the public trust doctrine establishes the role of the state as having trustee environmental duties owed to the public that are subsequently enforceable by the public. There is judicial recognition of this, dictating that certain rights of the public are key to individual common law rights (such as state recognition of the public right or trust for waterways and coastal zones). Judicial recognition of the public trust doctrine has been established for tidelands and non-navigable waterways, submerged land (such as lake beds) and the waters above them, and preservation of a public interest (such as recreation, swimming, access, and sport fishing). In National Audubon Society v. Superior Court, it was alleged by the plaintiffs that the public trust doctrine was being violated due to environmental damages to Mono Lake in the form of significant water level declines as a result of water diversions by the City of Los Angeles Department of Water and Power (DWP). DWP based their defense on the fact that they held permits, issued by the state for the diversions, and so the diversions were allowable. The central issue in the case was whether appropriative water rights (granted in the past) must consider the public trust doctrine, requiring protection of natural resources by the state. More specifically, the issue being addressed by the court was whether Mono Lake was subject to a public trust, which would invalidate Los Angeles' use of the streams feeding the lake. The California Supreme Court held that the state, under the public trust doctrine, had continuing responsibility for the state's navigable waters and that the public trust doctrine, therefore, prevented any party from appropriating water