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

(b) Approved maps. The appropriate maps for determining the boundary of the Diablo Grande viticultural area are the following four U.S.G.S. Quadrangle 7.5 Minute Series (Topographic) maps. They are titled:

(1) Patterson Quadrangle, California—Stanislaus Co., 1953 (Photorevised 1971, Photoinspected 1978);

(2) Copper Mtn. Quadrangle, California—Stanislaus Co., 1953 (Field Check 1956, Aerial Photo 1971);

(3) Wilcox Ridge, California—Stanislaus Co., 1956 (Photorevised 1971);

(4) Orestimba Peak, California—Stanislaus Co., 1955 (Photorevised 1971).

(c) Boundary. The Diablo Grande viticultural area is located in the western foothills of Stanislaus County, California. The beginning point is at Reservoir Spillway 780 in section 8, Township 6 South, Range 7 East (T. 6S., R. 7E.) on the Patterson Quadrangle U.S.G.S. map.

(1) Then proceed northwest to Salt Grass Springs to the point where the 1000 foot contour line crosses the northern section line of section 9, T. 6S., R. 6E., on the Copper Mtn., Quadrangle U.S.G.S. map.

(2) Then proceed due south past Copper Mountain in section 16, T. 6S., R. 6E., to Mikes Peak in section 4, T. 7S., R. 6E., on the Wilcox Ridge Quadrangle U.S.G.S. map.

(3) Then proceed due west to Oristimba Creek in section 6, T. 7S., R. 6E.

(4) Then proceed following Orestimba Creek south/southeast and then east/northeast to the point where Orestimba Creek meets Bench Mark #340 in section 28, T. 7S., R. 7E., on the Orestimba Peak Quadrangle U.S.G.S. map.

(5) Then proceed northwest to the point of beginning at Reservoir Spillway 780 in section 8, T. 6S., R. 7E.