(a) The districts consist of the following:
(1) District 1 is all that area in San Joaquin County east of Jack Tone Road or any extension of that road.
(2) District 2 is all that area in San Joaquin County north of Live Oak Road and west of Jack Tone Road or any extension of that road.
(3) District 3 is all that area in San Joaquin County not included in Districts 1 and 2, and all of Stanislaus County.
(4) District 4 is all of San Benito and Santa Clara Counties.
(5) District 5 is all other counties.
(b) The boundaries of any district may be changed by a two-thirds vote of the commission, which is concurred in by the director, to insure proper representation by producers. The boundaries need not coincide with county lines.