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Locat Sections Boundary Descriptions
Northern Local Sections
CENTRAL SAN JOAQUIN Fresno, Kings, Madera and Tulare Counties, in the Central Valley Region of the SWRCB regions.
MONTEREY BAY
Monterey, Santa Cruz, San Benito Counties, plus the portion of Santa Clara County south of Coyote.
NORTH COAST Del Norte, Humboldt, Trinity Counties, plus the portions of Siskiyou county west of the north-south line from the northern most point of Trinity County and at least 5 miles west of Highway I-5, plus the portion of Mendocino County north of Highway 20.
NORTHERN SAN JOAQUIN
Amador, Calaveras, Mariposa, Merced, San Joaquin, Stanislaus, Tuolumne Counties.
NORTH SACRAMENTO VALLEY Butte, Colusa, Glenn, Lassen, Modoc, Plumas, Shasta, Sierra, Sutter, Tehama, Yuba, Yolo counties, plus the portion of Siskiyou County east of the north-south line from the northern most point of Trinity County and at least 5 miles west of Highway I-5, and the portion of Nevada County in the Central Valley Region of the SWRCB regions.
REDWOOD EMPIRE Lake, Marin, Napa, Sonoma Counties, plus the portions of Mendocino County south of Highway 20, and that portion of Solano County west of Highway 680 and north of Highway 12.
SACRAMENTO AREA .Sacramento County, plus the portions of El Dorado and Placer Counties in the Central Valley Region of the SWRCB regions and the portion of Solano County south of Highway 12 and east of Highway 680.
SANTA CLARA VALLEY The portion of Santa Clara County north of Coyote and the portion of San Mateo County south of an east-west line from the Pacific Ocean to the Alameda County boundary just north of Millbrae.
SAN FRANCISCO BAY Alameda, Contra Costa and San Francisco Counties, plus the portion of San Mateo County north of the east-west line from the Pacific ocean to the Alameda County boundary.
SIERRA Alpine County, plus the portions of El Dorado, Mono, Nevada, and Placer Counties in the Northern Lahontan Region (north of Highway 167) of the SWRCB regions.
 
Southern Local Sections
COLORADO RIVER BASIN Imperial County plus portions of San Diego, Riverside and San Bernardino Counties. North boundary is Banning (inclusive) to Yucca Valley to Twentynine Palms to Amboy to Needles. East boundary is Needles to Yuma. South boundary is Yuma to San Diego county line. West boundary is San Diego County line to Highway 52 to Highway 79 to Highway 371 to Highway 74 to Highway 243 to Banning. (Anza-Borrego area, including Borrego Springs, is within the CORBS boundaries.)
DESERT AND MOUNTAIN
Inyo County plus portions of San Bernardino, and Mono Counties in the Southern Lahontan Region of the SWRCB. (Big Bear, Running Springs, Lake Arrowhead, and Crestline are within the Desert and Mountain Boundaries).
GOLDEN EMPIRE Kern County.
LOS ANGELES BASIN Los Angeles County.
SANTA ANA RIVER BASIN Orange County plus portions of San Diego and Riverside counties. North boundary is Los Angeles County line to Highway 10 to Highway 38. East boundary is from Highway 38 through Yucaipa to Beaumont to Highway 40 to Highway 243 to Highway 74 to Hemet to Highway R3 to San Diego County line. South boundary is Orange County line. (San Bernardino, Redlands, Yucaipa, San Jacinto, Idlywild, and Hemet are with the SARBS boundaries.
SAN DIEGO Portions of San Diego County. North boundary is San Diego County line south of San Clemente, east to Highway 79. East boundary is Highway 79 to Highway 52 to San Diego County line at Coyote Wells and follows County line to U.S./Mexico Border. (Anzo Borrego area, including Borrego Springs are not within San Diego Boundaries.)
TRI-COUNTIES San Luis Obispo, Santa Barbara and Ventura Counties.
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