(1) The equivalent population for each county shall be computed as the sum of the population residing in the county's unincorporated area plus twenty-five percent of the population residing in the county's incorporated area. Population figures required for the computations in this subsection shall be certified by the director of the office of financial management on or before July 1st of each odd-numbered year.
(2) The total annual road cost for each county shall be computed as the sum of one twenty-fifth of the total estimated county road replacement cost, plus the total estimated annual maintenance cost. Appropriate costs for bridges and ferries shall be included. The county road administration board shall be responsible for establishing a uniform system of roadway categories for both maintenance and construction and also for establishing a single statewide cost per mile rate for each roadway category. The total annual cost for each county will be based on the established statewide cost per mile and associated mileage for each category. The mileage to be used for these computations shall be as shown in the county road log as maintained by the county road administration board as of July 1, 1985, and each two years thereafter. Each county shall be responsible for submitting changes, corrections, and deletions as regards the county road log to the county road administration board. Such changes, corrections, and deletions shall be subject to verification and approval by the county road administration board prior to inclusion in the county road log.
(3) The money need factor for each county shall be the county's total annual road cost less the following four amounts:
(a) One-half the sum of the actual county road tax levied upon the valuation of all taxable property within the county road districts pursuant to RCW
36.82.040, including any amount of such tax diverted under chapter
39.89 RCW, for the two calendar years next preceding the year of computation of the allocation amounts as certified by the department of revenue;
(b) One-half the sum of all funds received by the county road fund from the federal forest reserve fund pursuant to RCW
28A.520.010 and
28A.520.020 during the two calendar years next preceding the year of computation of the allocation amounts as certified by the state treasurer;
(c) One-half the sum of timber excise taxes received by the county road fund pursuant to chapter
84.33 RCW in the two calendar years next preceding the year of computation of the allocation amounts as certified by the state treasurer;
(d) One-half the sum of motor vehicle license fees and motor vehicle and special fuel taxes refunded to the county, pursuant to RCW
46.68.080 during the two calendar years next preceding the year of computation of the allocation amounts as certified by the state treasurer.
(4) The state treasurer and the department of revenue shall furnish to the county road administration board the information required by subsection (3) of this section on or before July 1st of each odd-numbered year.
(5) The county road administration board, shall compute and provide to the counties the allocation factors of the several counties on or before September 1st of each year based solely upon the sources of information herein before required: PROVIDED, That the allocation factor shall be held to a level not more than five percent above or five percent below the allocation factor in use during the previous calendar year. Upon computation of the actual allocation factors of the several counties, the county road administration board shall provide such factors to the state treasurer to be used in the computation of the counties' fuel tax allocation for the succeeding calendar year. The state treasurer shall adjust the fuel tax allocation of each county on January 1st of every year based solely upon the information provided by the county road administration board.