The board of directors shall impose an annual special assessment on the benefited land to provide a fund to maintain, repair, and operate a watershed project constructed under this title. The amount of the annual special assessment shall be equal to the estimated cost to operate and maintain the watershed project as determined by an annual inspection to be made at a time set by the board of directors, less any amount that may be received from any other source. If the funds received under subsection (a) of this section are inadequate to provide for the necessary maintenance, repair, or operation, a supplemental assessment may be imposed on the benefited land. The assessments under this section shall be imposed and disbursed in the same manner as provided for the special assessments under § 25–803 of this subtitle.