This paper discusses briefly the water resource institutions and policies in the semi-arid State of California. Critical issues relevant to Water policies and institutions in arid and semi-arid regions based on experience in California are offered. California with its rapidly growing population due to both natural increase and immigration from other countries, and limited water resources, is, in the forefront among the fifty states in the U.S.A. in management of its water resources. A comprehensive set of institutions and policies, and comprehensive statewide inter-basin water transfer systems have been developed since the mid-l 800s. The institutions and policies are changing rapidly resulting from changes in the economy, in public needs, perceptions and attitudes, and from population growth. Major changes have resulted from court decisions in recent years. Changes have been embodied in statutes enacted by the Congress and the state legislature. A very important enactment was passage of the National Environmental Policy Act (NEPA) of 1969. This resulted in major changes in planning for the development and management of water resources, emphasizing protection and enhancement of environmental values, and protection of cultural and social values. INTRDDUCTlON In this paper, I will discuss briefly the water resources institutions and policies at the state government level in the State of California. That state, with its rapidly growing population due to both natural increase and immigration from other countries, and limited water resources, is, I believe, in the forefront among the fifty states in management of its water resources. A comprehensive set of institutions and policies, and comprehensive statewide inter-basin water transfer systems have been developed since the mid-1800s when the early gold miners found it necessary to divert from one stream and convey the water for use in a different watershed. But not all of the water resources problems have been solved, particularly agricultural drainage, groundwater pollution, and estuarine salinity control. The institutions and policies are changing rapidly resulting from changes in the economy, in public needs, perceptions and attitudes, and from population growth. Major changes have resulted from court decisions in recent years. Changes have been embodied in statutes enacted by the Congress and the state legislature. A very important enactment was passage of the National environmental Policy Act (NEPA) of 1969. This resulted in major changes in planning for the development and management of water resources, emphasizing protection and enhancement of environmental values, and protection of cultural and social values. More changes are anticipated.