Cal. Wat. Code § 47800
When a district has levied an assessment and it appears to the board that the assesssment or some part thereof, together with the interest thereon, will provide an amount greater than is required to meet all obligations incurred or to be incurred for the purposes for which the assessment or part thereof was levied, the board may, by resolution, declare its intention to cancel all or any portion of the assessment, including any interest thereon, or all or any portion of such interest. For the purposes of this chapter, the term "assessment balance" means the assessment and the interest thereon, and the board, in the manner and subject to the limitations provided in this chapter, may cancel any part of such assessment balance, including all of the assessment and the interest thereon, a part of the assessment and the interest thereon, all of the interest on the assessment or a part of the interest on the assessment.
Ca. Water Code § 47800