(a) Districts shall consist of the following:

(1) District 1 consists of Tulare, Kern, San Bernardino, San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, Riverside, San Diego, and Imperial Counties of California.

(2) District 2 consists of Kings, Fresno, Madera, and Merced Counties of California.

(3) District 3 consists of all counties in California where pistachios are produced that are not included in Districts 1 and 2.

(4) District 4 consists of the States of Arizona and New Mexico.

(b) With the approval of the Secretary, the boundaries of any district may be changed by the committee to ensure proper representation. The boundaries need not coincide with county lines.