Section 9.291 - Contra Costa(a)Name. The name of the viticultural area described in this section is "Contra Costa". For purposes of part 4 of this chapter, "Contra Costa" is a term of viticultural significance.(b)Approved maps. The 15 United States Geological Survey (USGS) 1:24,000 scale topographic maps used to determine the boundary of the Contra Costa viticultural area are titled:(1) Antioch North, California, 2018;(2) Antioch South, California, 2018;(3) Benicia, California, 2018;(4) Bouldin Island, California, 2018;(5) Briones Valley, California, 2018;(6) Byron Hot Springs, California, 2018;(7) Clayton, California, 2018;(8) Clifton Court Forebay, California, 2018;(9) Jersey Island, California, 2018;(10) Honker Bay, California, 2018;(11) Tassajara, California, 2018;(12) Vine Hill, California, 2018;(13) Walnut Creek, California, 1995;(14) Walnut Creek, California, 2018; and(15) Woodward Island, California, 2018.(c)Boundary. The Contra Costa viticultural area is located in Contra Costa County, California. The boundary of the Contra Costa viticultural area is as described as follows: (1) The beginning point is on the Bouldin Island map at the northernmost point of Holland Tract Road. From the beginning point, proceed south 1.9 miles along Holland Tract Road, crossing onto the Woodward Island map, to the intersection of the road with the 10-foot elevation contour; then(2) Proceed south-southeast in a straight line 4.1 miles to the intersection of Orwood Road and the Mokelumne Aqueduct; then(3) Proceed south-southwest in a straight line 5.5 miles, crossing onto the Clifton Court Forebay map, to the stream gauging station on Italian Slough, just west of the Widdows Island and the shared Contra Costa-San Joaquin County line; then(4) Proceed due west in a straight line to the western shore of Italian Slough, then proceed southwesterly along the western shore Italian Slough to its confluence with Brushy Creek; then(5) Proceed westerly along Brushy Creek, crossing onto the Byron Hot Springs map and continuing southwesterly along the creek to its intersection with Vasco Road; then(6) Proceed northwest in a straight line 4.3 miles to the intersection of Kellogg Creek and Walnut Boulevard; then(7) Proceed west-southwest in a straight line 2.9 miles, crossing onto the Tassajara map, to the intersection of Marsh Creek and Miwok Trail; then(8) Proceed northwesterly along Marsh Creek 2.4 miles, crossing onto the Antioch South map, to the creek's intersection with Deer Valley Road; then(9) Proceed northerly along Deer Valley Road 3.1 miles to its intersection with Chadbourne Road; then(10) Proceed northwest in a straight line 0.6 mile to the southwestern terminus of Tour Way; then(11) Proceed northwest in a straight line 3 miles to the intersection of Oil Canyon Trail, Stewartville Trail, and Chadbourne Road; then(12) Proceed northeasterly along Stewartville Trail 1.9 miles to its intersection with the Contra Loma Trail; then(13) Proceed northwest in a straight line 2.5 miles to the intersection of Somersville Road and Donlan Boulevard; then(14) Proceed west-southwest in a straight line 2.5 miles, crossing onto the Clayton map, to the intersection of Nortonville Road and Kirker Pass Road; then(15) Proceed southwesterly along Kirker Pass Road 5 miles to its intersection with Alberta Way; then(16) Proceed southwest in a straight line 1.5 miles to the intersection of Buckeye Trail, Blue Oak Trail, and Lime Ridge Trail; then(17) Proceed south-southeast in a straight line 2.6 miles to the intersection of Arroyo Cerro Del and the 400-foot elevation contour just east of North Gate Road; then(18) Proceed northwest in a straight line 2.5 miles, crossing onto the Walnut Creek map (2018 edition), to the intersection of Brodia Way and La Casa Via; then(19) Proceed west-northwest in a straight line, crossing onto the Walnut Creek (1995 edition) map, and continue 3.1 miles on the 1995 edition map to the marked 781-foot peak south of the shared Lafayette-Walnut Creek corporate boundary line and north of an unnamed light-duty road known locally as Peaceful Lane; then(20) Proceed northwest in a straight line 1.7 miles to the 833-foot peak marked "Hump 2"; then(21) Proceed north-northwest 0.5 mile to the water tank (known locally as the Withers Reservoir) at the end of an unnamed light-duty road known locally as Kim Road, in the Canada del Hambre y Las Bolsas Land Grant; then(22) Proceed northwest in a straight line 3 miles, crossing onto the Briones Valley map, to the intersection of Alhambra Creek Road and Alhambra Valley Road; then(23) Proceed northwest in a straight line 4.1 miles, crossing onto the Benicia map, to the intersection of Highway 4 and Cummings Skyway; then(24) Proceed north-northwest in a straight line 1.8 miles to the intersection of Carquinez Scenic Drive and an unnamed road known locally as Canyon Lake Drive; then(25) Proceed northeasterly in a straight line 0.6 mile to the marked post office in Port Costa; then(26) Proceed southeast in a straight line 0.9 mile to the first unnamed road that crosses the railroad tracks and intersects with the shoreline at Little Bull Valley; then(27) Proceed easterly along the shoreline approximately 38.3 miles, crossing over the Vine Hill, Honker Bay, and Antioch North maps and onto the Jersey Island map to Bethel Island Road; then(28) Proceed southeast in a straight line 0.7 mile to the intersection of Wells Road and Sandmound Boulevard; then(29) Proceed northeast in a straight line 2.7 miles, crossing onto the Bouldin Island map and returning to the beginning point.