Cal. Streets and Highways Code § 5837

The boundaries of any maintenance district may be altered, and contiguous or noncontiguous territory whether it is within incorporated or unincorporated territory may be annexed thereto. If incorporated territory is sought to be annexed, consent thereto shall first be obtained from the legislative body of the city. The board of supervisors may by resolution fix a time and place for hearing upon the question of annexation of such territory to an existing maintenance district. The resolution shall describe the boundaries of the territory proposed to be annexed. The board of supervisors may by resolution determine that each parcel of the territory annexed or to be annexed to a sewer maintenance district should pay its proportionate share of the cost of outfall and/or pumping plant construction previously paid for by other properties within said district and shall in said resolution fix the amount to be contributed by each said parcel. No parcel so annexed or to be annexed shall be issued a permit to connect to the sewer until the full amount of contribution so fixed has been paid. Any contribution whether heretofore or hereafter collected for such purposes shall be deposited in the county treasury to the credit of said district, or shall be held in trust until the parcel is included within the boundaries of the district at which time such contributions shall be transferred to the credit of said district. The date set for the hearing on the proposed annexation shall be at least three weeks from and after the date of the adoption of the resolution setting the hearing.