Cal. Pen. Code § 4126
The maximum amount per day to be credited to a person in custody on an industrial farm or camp shall be fixed from time to time by the board of supervisors and shall be as large as is justified by the production on the farm or camp but shall not exceed the sums mentioned in this article.
The superintendent of an industrial farm may by order cause an amount less than the maximum per day to be credited to any person because of lack of effort on the part of the person, the amount credited to be in proportion to the effort.
The sum to the credit of each person employed upon an industrial farm upon his discharge shall be paid him in addition to any transportation charge otherwise paid under this article. Any person may, by written order, direct the payment of any sums credited to him under this article to any person dependent upon him or to whom he is indebted.
Ca. Pen. Code § 4126