RCW 35.67.360

Any city, code city, town, county, special purpose district, municipal corporation, or quasi-municipal corporation that is engaged in the sale or distribution of stormwater or sewer services may use public moneys or credit derived from operating revenues from the sale of stormwater or sewer services to assist the owners of structures or equipment in financing the acquisition and installation of materials and equipment, for compensation or otherwise, for the conservation or more efficient use of stormwater or sewer services in such structures or equipment. Except for the necessary support of the poor and infirm, an appropriate charge-back shall be made for the extension of public moneys or credit. The charge-back shall be a lien against the structure benefited or a security interest in the equipment benefited.