(a) Name. The name of the viticultural area described in this section is “Yorkville Highlands.”

(b) Approved maps. The appropriate maps for determining the boundary of the Yorkville Highlands viticultural area are the following six U.S.G.S. topographical maps (7.5 minute series, 1:24000 scale):

(1) Gube Mountain, Calif., provisional edition 1991;

(2) Big Foot Mountain, Calif., provisional edition 1991;

(3) Cloverdale, Calif., 1960, photoinspected 1975;

(4) Ornbaun Valley Quadrangle, Calif., provisional edition, 1991;

(5) Yorkville, Calif., provisional edition, 1991;

(6) Hopland, Calif., 1960, photoinspected 1975.

(c) Boundary. The Yorkville Highlands viticultural area is located in Mendocino County, California. The boundary is as follows:

(1) The beginning point is Benchmark 680, located in Section 30, T. 12 N., R. 13 W., on the Ornbaum Valley quadrangle map;

(2) From the beginning point, the boundary proceeds in a straight line in a northeasterly direction to a point intersecting the North Fork of Robinson Creek and the Section 20, T. 13 N., R. 13 W.;

(3) The boundary then proceeds in a straight line in a southeasterly direction to the summit of Sanel Mountain, located at the southeast corner of Section 30, T. 13 N., R. 12 W., on the Yorkville quadrangle map;

(4) The boundary then proceeds in a straight line in a southeasterly direction until it reaches the southeast corner of Section 15, T. 12 N., R 11 W., on the Hopland quadrangle map;

(5) The boundary then proceeds south, following the eastern boundaries of Sections 22 and 27, T. 12 N., R 11 W., until it reaches the Mendocino-Sonoma County line on the Cloverdale quadrangle map;

(6) The boundary then follows the Mendocino-Sonoma county line west, south and west until it reaches the southwest corner of Section 32, T. 12 N., R. 11 W.;

(7) The boundary then diverges from the county line and proceeds in a northwesterly direction, traversing the Big Foot Mountain quadrangle map, until it reaches the southwest corner of Section 5, T. 12 N., R. 13 W. on the Ornbaun Valley quadrangle map;

(8) The boundary proceeds in a straight line in a northerly direction until it reaches the beginning point at Benchmark 680.