(a) Any county may make financial contributions to any watershed development authority created by special act of the general assembly, where a portion or all of the watershed development administered by such authority lies within the territory of such county.
(b) Such contributions shall only be made when authorized by the legislative body of such county, and from the general funds of the county. No special tax may be levied therefor.
(c) The amount of such contribution shall be as fixed by such county legislative body and sanctioned thereby as a county purpose, the development of which being beneficial to such county.