Wash. Rev. Code § 39.92.010
The legislature finds that there is an increasing need for local and regional transportation improvements as the result of both existing demands and the foreseeable future demands from economic growth and development within the state, including residential, commercial, and industrial development.
The legislature intends with this chapter to enable local governments to develop and adopt programs for the purpose of jointly funding, from public and private sources, transportation improvements necessitated in whole or in part by economic development and growth within their respective jurisdictions. The programs should provide a fair and predictable method for allocating the cost of necessary transportation improvements between the public and private sectors. The programs should include consideration of public transportation as a method of reducing off-site transportation impacts from development. The legislature finds that the private funds authorized to be collected pursuant to this chapter are for the purpose of mitigating the impacts of development and are not taxes. The state shall encourage and give priority to the state funding of local and regional transportation improvements that are funded in part by local, public, and private funds.
The authority provided by this chapter, RCW 35.43.182 through 35.43.188, and 36.88.072 through 36.88.078 for local governments to create and implement local transportation programs is intended to be supplemental, except as expressly provided in RCW 39.92.030(9), 82.02.020, and 36.73.120, to the existing authorities and responsibilities of local governments to regulate development and provide public facilities.
RCW 39.92.010