WSDOT shall incorporate BMPs in all new construction projects for which design is started after the effective date of this chapter. For projects that are being designed or constructed when this chapter becomes effective, WSDOT shall implement BMPs to the maximum extent practicable to protect water quality. If the cost of constructing water quality BMPs makes a project that is being designed when this chapter becomes effective impracticable, then such BMPs shall be retrofitted at a later date. WSDOT shall submit water pollution control plans to ecology for review and approval for new construction and shall obtain other appropriate authorizations prior to construction.