HB 1010 authorizes Washington counties to allow detached accessory dwelling units on rural properties of any size, subject to specified requirements. These units must comply with water supply standards, sewage system capacity requirements, and limitations on size (1,296 square feet maximum) and placement to protect critical areas and agricultural/forestland. Counties authorizing such units must update their comprehensive plans accordingly, and population growth from compliant units does not count toward rural or urban growth targets. The bill also adds definitional clarity regarding accessory dwelling units and clarifies how detached accessory dwelling units relate to agricultural zoning provisions.