Cal. Pub. Util. Code § 30261

The board may provide by resolution, under such terms and conditions as it sees fit, for the payment of demands against the district without prior specific approval thereof by the board if the demand is for a purpose for which an expenditure has been previously approved by the board and in an amount no greater than the amount so authorized, and if the demand is approved by the general manager or such other officer or deputy as the board may prescribe.