(1) The superintendent of public instruction shall phase-in the implementation of the distribution formula under this chapter for allocating state funds to school districts for the transportation of students to and from school. The phase-in shall begin no later than the 2011-2013 biennium and be fully implemented by the 2013-2015 biennium.
(a) The formula must be developed and revised on an ongoing basis using the major cost factors in student transportation, including basic and special student loads, school district land area, average distance to school, roadway miles, and number of locations served. Factors must include all those site characteristics that are statistically significant after analysis of the data required by the revised reporting process.
(b) The formula must allocate funds to school districts based on the average predicted costs of transporting students to and from school, using a regression analysis. Only factors that are statistically significant shall be used in the regression analysis. Employee compensation costs included in the allowable transportation expenditures used for the purpose of establishing each school district's independent variable in the regression analysis shall be limited to the base salary or hourly wage rates, fringe benefit rates, and applicable health care rates provided in the omnibus appropriations act.
(2) During the phase-in period, funding provided to school districts for student transportation operations shall be distributed on the following basis:
(a) Annually, each school district shall receive the lesser of the previous school year's pupil transportation operations allocation, or the total of allowable pupil transportation expenditures identified on the previous school year's final expenditure report to the state plus district indirect expenses using the federal restricted indirect rate as calculated in the district annual financial report;
(b) Annually, the amount identified in (a) of this subsection shall be adjusted for any budgeted increases provided in the omnibus appropriations act for salaries or fringe benefits;
(c) Annually, any funds appropriated by the legislature in excess of the maintenance level funding amount for student transportation shall be distributed among school districts on a prorated basis using the difference between the amount identified in (a) adjusted by (b) of this subsection and the amount determined under the formula in RCW
28A.160.180; and
(d) Allocations provided to recognize the cost of depreciation to districts contracting with private carriers for student transportation shall be deducted from the allowable transportation expenditures in (a) of this subsection.