(a) Name. The name of the viticultural area described in this section is “Coombsville”. For purposes of part 4 of this chapter, “Coombsville” is a term of viticultural significance.

(b) Approved maps. The two United States Geological Survey 1:24,000 scale topographic maps used to determine the boundary of the Coombsville viticultural area are titled:

(1) Mt. George Quadrangle, California, 1951, Photoinspected 1973; and

(2) Napa Quadrangle, California-Napa Co., 1951, Photorevised 1980.

(c) Boundary. The Coombsville viticultural area is located in Napa County, California. The boundary of the Coombsville viticultural area is as described below:

(1) The beginning point is on the Mt. George map at the 1,877-foot peak of Mt. George, section 29, T6N/R3W. From the beginning point, proceed southeast in a straight line for 0.4 mile to the intersection of the 1,400-foot elevation line and an unnamed intermittent creek that feeds northeast into Leonia Lakes, section 29, T6N/R3W; then

(2) Proceed east-southeast in a straight line for 0.45 mile to the intersection of the 1,380-foot elevation line and an unnamed, unimproved dirt road, and then continue in the same straight line to the section 29 east boundary line, T6N/R3W; then

(3) Proceed south-southeast in a straight line for 0.6 mile to the unnamed 1,804-foot elevation point in the northwest quadrant of section 33, T6N/R3W; then

(4) Proceed south-southwest in a straight line for 1 mile, passing over the marked 1,775-foot elevation point, to the intersection of the T6N and T5N common line and the 1,600-foot elevation line; then

(5) Proceed south-southeast in a straight line for 1.1 miles to the 1,480-foot elevation point along the section 9 north boundary line, T5N/R3W; then

(6) Proceed south-southwest in a straight line for 1.3 miles to the 1,351-foot elevation point, section 16, T5N/R3W; then

(7) Proceed south-southwest in a straight line for 1.5 miles to the intersection with two unimproved dirt roads and the 1,360-foot elevation line in Kreuse Canyon at the headwaters of the intermittent Kreuse Creek, northeast of Sugarloaf, section 20, T5N/R3W; then

(8) Proceed northwest in a straight line for 1.95 miles to the 90-degree turn of Imola Avenue at the 136-foot elevation point, section 13, T5N/R4W; then

(9) Proceed west along Imola Avenue for 2.1 miles, crossing from the Mt. George map onto the Napa map, to the intersection of Imola Avenue with the Napa River at the Maxwell Bridge, T5N/R4W; then

(10) Proceed north (upstream) along the Napa River for 3.2 miles, crossing over the T6N/T5N common line, to the intersection of the Napa River with Milliken Creek, T6N/R4W; then

(11) Proceed north (upstream) along Milliken Creek for 0.75 mile to the intersection of Milliken Creek with Monticello Road, T6N/R4W; then

(12) Proceed northeast along Monticello Road for 2.4 miles, crossing from the Napa map onto the Mt. George map, to the intersection of Monticello Road with the section 19 west boundary line, T6N/R3W; and then

(13) Proceed east-southeast in a straight line for 1.4 miles to the beginning point, section 29, T6N/R3W.