Cal. Water Code § 31144.77

(a) After the establishment of a zone in which a groundwater charge may be levied, each owner or operator of a water-producing facility within the zone, until such time as the water-producing facility has been permanently abandoned, shall file with the district, on or before the 30th day following the end of collection periods established by the board, a water production statement setting forth the total production in acre-feet of water for the preceding collection period, a general description or number locating each water-producing facility, the method or basis of the computation of that water production, and the amount of the groundwater charge based on that computation. The collection periods may be established at not greater than a year or less than six months. If no water has been produced from the water-producing facility during a preceding collection period, this statement shall be filed, setting forth that no water has been produced during that period. The statement shall be verified by a written declaration that it is made under the penalties of perjury. The groundwater charge is payable to the district on or before the last date upon which the water production statements shall be filed, and is computed by multiplying the production in acre-feet of water for each classification as disclosed in the statement by the groundwater charge for each classification of water. At the time any water-producing facility has been permanently abandoned, the operator shall give written notice of the abandonment to the district. If any operator of a water-producing facility fails to pay the groundwater charge when due, the district shall charge interest at the rate of 1 percent each month on the delinquent amount of the groundwater charge.
(b) If any owner or operator of a water-producing facility fails to register each water-producing facility, or fails to file the water production statements as required by this article, the district shall, in addition to charging interest as provided, assess a penalty charge against that owner or operator in subdivision (a), an amount of 10 percent of the amount found by the district to be due. The board may adopt regulations to provide that in excusable or justifiable circumstances the penalty may be reduced or waived.
(c) When a water-measuring device is permanently attached to a water-producing facility, the record or production as disclosed by that water-measuring device shall be presumed to be accurate and shall be used as the basis for computing the water production of that water-producing facility in completing the water production statement, unless it can be shown that the water-measuring device is not measuring accurately.
(d) When a water-measuring device is not permanently attached to a water-producing facility, the board may establish a method or methods to be used in computing the amount of water produced from the water-producing facility. The methods may be based upon any, or any combination, of the following criteria:
1. (1) The minimum charge sufficient to cover administrative costs of collection.
2. (2) The size of the water-producing facility discharge opening.
3. (3) The area served by the water-producing facility.
4. (4) The number of persons served by the water-producing facility.
5. (5) The use of land served by the water-producing facility.
6. (6) Any other criteria which may be used to determine with reasonable accuracy the amount of water produced from the water-producing facility.
(e) The district may levy an annual charge upon a water-producing facility for which no production has been recorded but which has not been permanently abandoned, except that this charge shall not exceed the annual cost to the district of maintaining and administering the registration of that facility.