The bill amends existing growth management statutes (RCW 36.70A.060 and RCW 36.70A.108). It explicitly allows any county that borders both the Cascade mountains and "another country" and has a population under 50,000, and any city in such a county, to adopt development regulations permitting agricultural, forest, and mineral resource lands adjacent to short line railroads to be developed for freight rail dependent uses. The amended RCW 36.70A.060 otherwise retains existing requirements that counties and cities adopt regulations to conserve designated resource lands, that preexisting legal uses not be prohibited, and that plats, short plats, development permits, and building permits for development on or within 500 feet of designated resource lands contain notices about proximity to those lands (and, for mineral resource lands, that mining-related activities may be applied for). The amendment to RCW 36.70A.108 allows a transportation element of a comprehensive plan to include multimodal transportation improvements or strategies made concurrent with development and to include measures implementing or evaluating multiple modes with peak and nonpeak hour capacity performance standards and corresponding modal performance standards. The section also clarifies that nothing in these provisions or RCW 36.70A.070(6)(b) is intended to prohibit jurisdictions planning under RCW 36.70A.040 from using existing authority to develop multimodal improvements or strategies to meet concurrency requirements, and that the amendments do not change the authority of those jurisdictions. The bill also preserves and restates procedural provisions tied to partial planning resolutions and compliance: counties adopting a resolution of partial planning must adopt development regulations within one year; a county not in compliance was required to apply for a department determination of compliance by January 30, 2017, with the department required to act within 120 days or by June 30, 2017; petitions for review of department determinations go to the growth management hearings board within 60 days; and if a petition is filed the county and the department must equally share the department’s defense costs. A city with fewer than 25,000 may adopt county critical areas regulations by reference, must incorporate future county amendments, is exempt from separately updating those critical areas under RCW 36.70A.130, and the county is entitled to the portion of periodic planning grant funding that would otherwise pay for the city’s updates as determined by the department. The text provided does not identify which specific agency is meant by "the department," does not define key terms such as "freight rail dependent uses" or "short line railroad," and does not explain the phrase "another country" or provide detailed language about any required "freight rail dependent use overlay," so those points remain unclear from the extracted material.

If enacted, the bill gives a narrow set of small counties (those under 50,000 people that border the Cascade mountains and an unspecified "other country") and their cities the option to allow agricultural, forest, and mineral resource lands next to short line railroads to be used for freight rail–dependent businesses. That will expand development choices for landowners and developers near short line rail lines and could attract rail-oriented investment in those counties, while local governments gain a new zoning tool but also must draft and adopt the necessary development regulations. Because conservation requirements and notice rules for plats and permits within 500 feet of resource lands remain, affected property owners will still face proximity notices and potential mining-notification requirements; however, which counties qualify, and what exactly counts as a "freight rail dependent use" or a "short line railroad," is not defined here, leaving important implementation questions to local ordinance writing and the unnamed state department's rulemaking and determinations. The changes to the transportation element let local planners include multimodal projects and peak/nonpeak capacity or modal performance standards as part of concurrency planning, giving counties and cities more flexibility to meet transportation requirements with multimodal improvements. Smaller cities that adopt county critical areas regulations by reference will shift update responsibilities to the county and the county will be entitled to the portion of periodic planning grant funding tied to those updates, changing where grant dollars and regulatory workload sit. Existing compliance, appeal, and cost‑sharing procedures remain in force—counties face deadlines to adopt regulations, department review and possible appeals to the growth management hearings board, and shared legal-defense costs if appeals occur—so there may be added administrative and potential legal expenses for local governments.