(a) Subject to the overriding provisions of § 3.40-5, Sector Houston-Galveston's Marine Inspection Zone and Captain of the Port Zone start near the intersection of the western boundary of Vermillion Parish, LA, and the sea at latitude 29°34′45″ N, longitude 92°37′00″ W, proceeding north along the eastern and southern boundaries of Cameron, Jefferson Davis, Allen, and Rapides Parishes, LA, to the southern bank of the Red River; thence northwest along the south bank of the Red River to the northern boundary of Red River Parish, LA; thence west along the northern boundary of Red River Parish and DeSoto Parish, LA, to the Louisiana-Texas border; thence north along the Louisiana-Texas border to the Texas-Arkansas border at the northern boundary of Bowie County, TX; thence west along the Texas-Arkansas border to the Texas-Oklahoma border; thence northwest along the Texas-Oklahoma border to the southern shore of Lake Texoma in Grayson County, TX; thence west along the northern shore of Lake Texoma to the Texas-Oklahoma border; thence west along the Texas-Oklahoma border to the Texas-New Mexico border, including all portions of the Red River; thence south along the Texas-New Mexico border to the southern boundary of Andrews County, TX; thence southeast along the western and southern boundaries of Andrews, Midland, Glasscock, Sterling, Tom Green, Concho, McCulloch, San Saba, Lampasas, Bell, Williamson, Lee, Washington, and Austin Counties, TX to the intersection of Colorado County, Texas; thence along the northern and eastern boundary of Colorado County to the east bank of the Colorado River; thence south along the east bank of the Colorado River to the sea; thence southeast along a line bearing 140° T to the outermost extent of the EEZ at latitude 25°59′50″ N, longitude 93°32′21″ W; thence east along the outermost extent of the EEZ to latitude 26°03′27″ N, longitude 92°37′00″ W; thence north along longitude 92°37′00″ W to the Louisiana Coast; and in addition, all the area described in paragraph (b) of this section.

(b) The boundaries of the MSU Port Arthur Marine Inspection and Captain of the Port Zones start at the intersection of the sea and longitude 92°37′00″ W; thence north along the eastern and southern boundaries of Cameron, Jefferson Davis, Allen, and Rapides Parishes, Louisiana to the southern bank of the Red River; thence northwest along the southern bank of the Red River to the northern boundary of Red River Parish, Louisiana; thence west along the northern boundary of Red River Parish and Desoto Parish, Louisiana to the Louisiana-Texas border; thence north along the Louisiana-Texas border to the Texas-Arkansas border at the northern boundary of Bowie County, Texas; thence north along the Texas-Arkansas border to the Texas-Oklahoma border; thence west along the Texas-Oklahoma border to the northwest-most boundary of Fannin County, Texas, including all portions of the Red River; thence south along the western and southern boundaries of Fannin, Hunt, Kaufman, Henderson, Anderson, Houston, Trinity, Polk, Hardin, and Jefferson Counties, Texas to the sea at longitude 94°25′00″ W; thence southeast to latitude 29°00′00″ N, longitude 93°40′00″ W; thence southeast to latitude 27°50′00″ N, longitude 93°24′00″ W; thence south along longitude 93°24′00″ W to the outermost extent of the EEZ; thence east along the outermost extent of the EEZ to longitude 92°37′00″ W; thence north along longitude 92°37′00″ W to the Louisiana Coast.