As used in this chapter, unless the context requires a different meaning: “Rivanna River Basin” means that land area designated as the Rivanna River Basin by the State Water Control Board pursuant to § 62.1-44.38 and that is also found in the Fifteenth, Seventeenth, Twenty-fourth and Twenty-fifth state Senatorial districts or the Twenty-fifth, Fifty-seventh, Fifty-eighth and Fifty-ninth House of Delegates districts, as those districts existed on January 1, 2002.