Cal. Water Code § 5004

After the year 1959, failure to file with the board a notice for any calendar year within six months after the close of such calendar year shall be deemed equivalent for all purposes to nonuse for such year of any ground water within the four counties by each person failing to so file a notice within said period; provided, that this section and Section 5003 shall not apply to any person whose aggregate extractions of ground water in any year does not exceed 25 acre-feet nor to any extractions of ground water with respect to which no notice is required to be filed under this part.