The county legislative body of any county, any part of which is located within a watershed district, or the governing body of any city or town within, adjacent to or in the proximity of a watershed district, has the right to contribute, out of the general fund of such county or city, such amount as such legislative body sees fit, to be used in the preliminary expenses of the district, or in the maintenance of the district, or for capital improvements or projects of the district. County legislative bodies and governing bodies of cities or towns are empowered to levy and collect ad valorem taxes for the purpose of contributing to a watershed district, which are hereby declared to be for municipal and county public purposes.