Cal. Water Code § 34713

A person elected on the basis of one man-one vote to the board of directors of a California water district, which district has been authorized by the Legislature to convert on a phased basis from a landowner voting basis to a one man-one vote basis, may serve out the remainder of the elected term after being elected, for the first time, to the office of director of a municipal water district which encompasses, in whole or in part, the California water district.