This bill adds a new section to chapter 36.70A RCW allowing counties to authorize detached accessory dwelling units (DADUs) outside urban growth areas if the county adopts specified development rules and enforcement procedures, and it amends RCW 36.70A.696 so the listed definitions apply to the new section and several related sections. In short, it creates a new statutory option for counties and modifies the existing definitions statute; it also imposes new procedural requirements and penalties tied to DADU approval and enforcement. Substantive requirements for DADUs include one ADU per parcel; compliance with RCW 19.27.097 and any Department of Ecology groundwater mitigation requirements; documentation that the existing or proposed septic system can handle the additional demand; a gross floor area no larger than what could be authorized as an attached ADU expansion and in no case larger than 1,296 square feet (excluding garages, porches, and unfinished basements); use of the same driveway as the principal unit; siting within 150 feet of the principal unit; prohibition on subdividing parcels to evade limits; meterization of each dwelling’s water withdrawals and limits so combined withdrawals do not exceed RCW 90.44.050; and a rule that if a DADU is offered as a short-term rental the primary unit must be owner-occupied. The bill requires counties to adopt specified code enforcement procedures and penalties: a voluntary compliance path that imposes at least double the normal permit fee for bringing an unpermitted DADU into compliance; a civil infraction of at least $1,000 for owners who do not seek voluntary compliance and who constructed or placed a DADU without required permits, with an obligation to remove the DADU or make it compliant; if an unpermitted DADU remains and meets regulations after enforcement, a penalty of at least triple the normal permit fee applies; and owners who received a civil infraction for unpermitted ADU construction are barred from receiving permits for new ADUs for at least three years. Counties must also track and report annual DADU permit completions to “the department,” update comprehensive plans at their next RCW 36.70A.130(5)(b) review to account for completed and projected DADUs over a 20-year period, and may make subsequent amendments to account for DADUs no more than once every five years. The section is stated to be in addition to other county ADU authority and does not invalidate prior county ADU ordinances. Important gaps in the provided text: the specific agency referred to as “the department” is not identified, the exact new section number added to chapter 36.70A RCW is not shown, the effective date is not provided, and “normal permit fee” is not defined. The description of “overall underlying density outside urban growth areas” relies on other statutes not included here.

If enacted, counties would be able to allow detached accessory dwelling units (DADUs) outside urban growth areas, giving property owners an extra option to add housing on rural parcels but only if they meet strict siting, size (up to 1,296 sq ft), shared driveway, water, septic, metering, and proximity (within 150 feet) rules. Owners who build without following the rules face real costs and risks: a voluntary compliance path requires paying at least double the normal permit fee, failure to seek compliance can trigger a civil infraction of at least $1,000 and either removal or bringing the unit into compliance (or paying at least triple the permit fee), and a civil infraction can bar an owner from new ADU permits for three years; short-term rental use of a DADU also forces the primary unit to be owner-occupied. Counties will have new ongoing responsibilities and modest enforcement revenue potential: they must run a voluntary compliance program, enforce penalties, track and report DADU permit counts annually to an unspecified “department,” and update their comprehensive land use plans at the next required review to account for DADUs and projected 20‑year development, with further plan amendments allowed no more than once every five years. Key details are missing from the provided text—most notably which agency is “the department,” the effective date, and how the “normal permit fee” and underlying density calculations will be determined—so some implementation and fiscal impacts remain uncertain.