A board of viewers: shall determine the amount sufficient to pay: the cost of a proposed watershed project; any damages awarded; any compensation for an existing watershed project that the board of viewers adopts in accordance with § 25–504 of this subtitle; the expenses of the board of viewers; and the costs of establishing the watershed association; shall subtract from the amount determined under item (1) of this subsection any amounts in money or service received from the county or any other source; shall assess each tract of land in the area affected by the watershed association a proportion of the amount described in item (2) of this subsection, based on the benefits that would accrue to the tract of land from the watershed project; and may not assess a tract of land for an amount that is more than the benefits that would accrue to the tract of land from the watershed project. Notwithstanding any other law, the county commissioners, county council, or Mayor and City Council of Baltimore City may: contribute in money, services, equipment, or materials toward the costs of any watershed project authorized under this title from general funds of the county; or allocate toward the costs of any watershed project any other money that is available for the watershed project.