California Code, Water Code - WAT § 51335.5

In the event the assessment for any parcel of land separately assessed, based upon the rate fixed pursuant to Section 51335, is less than twenty-five dollars ($25), a minimum assessment may be set by the board at an amount determined by the board to be adequate to defray the cost of collecting each minimum assessment, but which shall not exceed twenty-five dollars ($25) for each separately assessed parcel of land.