Notwithstanding Section 1304 of the Elections Code, the board of an irrigation district containing 500,000 acres or more may designate that the general district election shall be held on the day provided for the statewide direct primary election in Section 1201 of the Elections Code and consolidated with the statewide primary election, and thereafter all references to odd-numbered years with respect to those elections shall mean even-numbered years as nearly as may be applicable. A designation by the board changing the date of a general district election pursuant to this section shall be adopted by resolution of the board and filed with the county clerk of the principal county at least 90 days before the date of the next district general election that would occur had the designation not been made and at least 90 days before the next statewide direct primary election provided for in Section 1201 of the Elections Code.