# 9.166 Diamond Mountain District.
(a) *Name.* The name of the viticultural area described in this section is “Diamond Mountain District.”
(b) *Approved map.* The appropriate maps for determining the boundary of the Diamond Mountain District viticultural area are two 1:24,000 Scale U.S.G.S. topography maps. They are titled:
(1) Mark West Springs, CA 1993
(2) Calistoga, CA 1993.
(c) *Boundaries.* The viticultural area is located in Napa County, California. The beginning point is where the boundary between Napa and Sonoma counties intersects Petrified Forest Road in Section 3 of Township 8 North, Range 7 West, Mount Diablo Base and Meridian on the Mark West Springs map;
(1) Then north and east along Petrified Forest Road approximately 1.9 miles to the point where it intersects the 400-foot contour just east of Section 35 of Township 9 North, Range 7 West, Mount Diablo Base and Meridian, in the Mallacomes land grant;
(2) Then generally east southeast along the 400-foot contour approximately 6.5 miles to the point where it intersects Ritchey Creek in Section 3 of Township 8 North, Range 6 West, Mount Diablo Base and Meridian;
(3) Then west southwest along Ritchey Creek approximately 2.2 miles to the point where it intersects the boundary between Sections 17 and 20 of Township 8 North, Range 6 West, Mount Diablo Base and Meridian;
(4) Then due west in a straight line along the section boundary approximately 0.8 miles to the point where it intersects the boundary between Napa and Sonoma Counties between Sections 18 and 19 of Township 8 North, Range 6 West, Mount Diablo Base and Meridian;
(5) Then generally northwest along the boundary between Napa and Sonoma Counties approximately 4.2 miles to the point where it intersects Petrified Forest Road, to the point of beginning.
[T.D. ATF-456, 66 FR 29698, June 1, 2001]