RCW 86.09.385

As a basis for the levy of all assessments authorized under this chapter, the county legislative authority of the county within which the major portion of the district is situated, soon after the creation of the district, shall cause to be prepared a base map of the lands within the district and deliver the same to the secretary of the district: PROVIDED, That said county legislative authority shall not be required to prepare said base map unless ample appropriation of funds for the purpose has been made.