(a) “Districts” consist of the following:
(1) District 1 consists of Butte County.
(2) District 2 consists of Colusa County.
(3) District 3 consists of Glenn County and Tehama County, and any county north of those counties where rice is produced.
(4) District 4 consists of Yuba and Sutter Counties.
(5) District 5 consists of Sacramento, San Joaquin, Placer, and Yolo Counties and any county south of those counties where rice is produced.
(b) The commission, upon a two-thirds vote of the membership of the commission, may change the districts.