Article 1. Water Subject To Appropriation of California Water Code >> Division 2. >> Part 2. >> Chapter 1. >> Article 1.

Whenever the terms stream, lake or other body of water, or water occurs in relation to applications to appropriate water or permits or licenses issued pursuant to such applications, such term refers only to surface water, and to subterranean streams flowing through known and definite channels.

All water flowing in any natural channel, excepting so far as it has been or is being applied to useful and beneficial purposes upon, or in so far as it is or may be reasonably needed for useful and beneficial purposes upon lands riparian thereto, or otherwise appropriated, is hereby declared to be public water of the State and subject to appropriation in accordance with the provisions of this code.

The following are hereby declared to constitute unappropriated water:
  (a) All water which has never been appropriated.
  (b) All water appropriated prior to December 19, 1914, which has not been in process, from the date of the initial act of appropriation, of being put, with due diligence in proportion to the magnitude of the work necessary properly to utilize it for the purpose of the appropriation, or which has not been put, or which has ceased to be put to some useful or beneficial purpose.
  (c) All water appropriated pursuant to the Water Commission Act or this code which has ceased to be put to the useful or beneficial purpose for which it was appropriated, or which has been or may be or may have been appropriated and is not or has not been in the process of being put, from the date of the initial act of appropriation, to the useful or beneficial purpose for which it was appropriated, with due diligence in proportion to the magnitude of the work necessary properly to utilize it for the purpose of the appropriation.
  (d) Water which having been appropriated or used flows back into a stream, lake or other body of water.

Any water the right to the use of which is held by any municipality which is in excess of the existing municipal needs therefor may be appropriated by any person entitled to the possession of land upon which such excess water may be put to beneficial use but the right of such person to use such water shall continue only for such period as the water is not needed by the municipality. This section supplements but does not otherwise affect Sections 1460 to 1464, inclusive.