2023 California Code › Water Code - WAT › DIVISION 3 - DAMS AND RESERVOIRS › PART 1 - SUPERVISION OF DAMS AND RESERVOIRS › CHAPTER 1 - Definitions › Section 6004.

6004. (a) An obstruction in a canal used to raise or lower water therein or divert water therefrom, a levee, including, but not limited to, a levee on the bed of a natural lake with the primary purpose to control floodwaters, a railroad fill or structure, a road or highway fill or structure, a circular tank constructed of steel or concrete, or both, a tank elevated above the ground, and a barrier that is not across a stream channel, watercourse, or natural drainage area and that has the principal purpose of impounding water for agricultural use shall not be considered a dam.
(b) An obstruction in the channel of a stream or watercourse that is 15 feet or less in height from the lowest elevation of the obstruction and that has the single purpose of spreading water within the bed of the stream or watercourse upstream from the obstruction for percolation underground shall not be considered a dam.
(c) The levee of an island adjacent to tidal waters in the Sacramento-San Joaquin Delta, as defined in Section 12220, even when used to impound water, shall not be considered a dam and the impoundment shall not be considered a reservoir if the maximum possible water storage elevation of the impounded water does not exceed four feet above mean sea level, as established by the United States Geological Survey 1929 datum.
(d) A noncircular tank, constructed of steel or concrete, or both, that is constructed in a county of the third class by a public agency, under the supervision of a civil engineer registered in the state, that does not exceed 75 acre-feet in capacity or 30 feet in height, and a barrier that is not across a stream channel, watercourse, or natural drainage area and that has the principal use as a sewage sludge drying facility, shall not be considered a dam.
(e) (1) A regulating basin owned or operated by a public entity that is not across a stream channel, watercourse, or natural drainage shall not be considered a dam if all of the following criteria are met:
(A) The barrier constructed to form the regulating basin has a height of no more than 15 feet from the crest to the lowest downstream elevation where the barrier meets natural ground.
(B) The regulating basin has a storage capacity of no more than 1,500 acre-feet.
(C) The regulating basin, at the time of construction, does not have a downstream hazard classification of “high” or “extremely high,” based upon the department’s criteria for those determinations.
(D) The regulating basin is designed, and its construction is overseen, by a licensed civil engineer.
(E) The regulating basin is compliant with the general plan of the county in which it is located.
(2) In order for a regulating basin to qualify for the exclusion under paragraph (1), the owner or operator of the regulating basin shall do all of the following:
(A) Before the construction of the regulating basin, submit to the department an inundation map, stamped by a licensed civil engineer, identifying the flow and depth of water from the regulating basin in the event of a failure of a barrier constructed to form the regulating basin.
(B) Undertake an inspection, conducted by a licensed civil engineer, of all barriers and all appurtenant structures of the regulating basin every two years following the regulating basin’s construction, and make the report available on the operating agency’s internet website.
(C) Immediately upon the identification of a failure or the risk of failure of a barrier or works critical to the safe operation of the regulating basin, notify the county sheriff and local emergency managers of all properties likely to be impacted by a failure, in accordance with the identification of those properties on the map submitted pursuant to subparagraph (A).
(f) For purposes of this section, the following definitions apply:
(1) “Licensed civil engineer” means a civil engineer licensed pursuant to Chapter 7 (commencing with Section 6700) of Division 3 of the Business and Professions Code.
(2) “Natural drainage” means a land area over which seasonal precipitation or natural spring water accumulates and is channelized directly into a stream or watercourse.
(3) “Regulating basin” means a reservoir constructed to impound and manage the inflow and delivery of water for agricultural uses or for the purpose of groundwater recharge or other actions undertaken to implement the Sustainable Groundwater Management Act (Part 2.74 (commencing with Section 10720) of Division 6).
(Amended by Stats. 2022, Ch. 943, Sec. 1. (AB 1164) Effective January 1, 2023.)