27 CFR § 9.23 - Napa Valley.
(a) Name. The name of the viticultural area described in this section is “Napa Valley.”
(b) Approved maps. The maps showing the boundaries of the Napa Valley viticultural area are the:
(1) “Mt. St. Helena” U.S.G.S. 7.5 minute quadrangle;
(2) “Detert Reservoir” U.S.G.S. 7.5 minute quadrangle;
(3) “St. Helena” U.S.G.S. 15 minute quadrangle;
(4) “Jericho Valley” U.S.G.S. 7.5 minute quadrangle;
(5) “Lake Berryessa” U.S.G.S. 15 minute quadrangle;
(6) “Mt. Vaca” U.S.G.S. 15 minute quadrangle;
(7) “Cordelia” U.S.G.S. 7.5 minute quadrangle;
(8) “Cuttings Wharf” U.S.G.S. 7.5 minute quadrangle; and
(9) Appropriate Napa County tax assessor's maps showing the Napa County-Sonoma County line.
(c) Boundaries. The Napa Valley viticultural area is located within Napa County, California. From the beginning point at the conjuction of the Napa County-Sonoma County line and the Napa County-Lake County line, the boundary runs along—
(1) The Napa County-Lake County line;
(2) Putah Creek and the western and southern shores of Lake Berryessa;
(3) The Napa County-Solano County line; and
(4) The Napa County-Sonoma County line to the beginning point.