Cal. Water Code - WAT § 8100. Section 8100.
Under such limitations and restrictions as are prescribed by law, and in addition to jurisdiction and powers otherwise conferred, the boards of supervisors, in their respective counties, may appropriate and expend money from the general fund of the county for any of the following purposes in connection with streams or rivers in the county:
(a)
The construction of works, improvements, levees or check dams to prevent overflow and flooding.
(b)
The protection and reforestation of watersheds.
(c)
The conservation of the flood waters.
(d)
The making of all surveys, maps and plats necessary to carry out any work, construction or improvement authorized by this article.
(e)
The carrying out of any work, construction or improvement authorized by this article outside the county if the rivers or streams affected flow in or through more than one county.