administrative action set out in Williams v. Seattle Sch. Dist. 1, 97 Wn.2d 215, 218-19, 643 P.2d 426 (1982). Williams, however, along with Washington Fed'n of State Employees v. State Personnel Bd., 23 Wn. App. 142, 145-46, 594 P.2d 1375 (1979), were cases in which an administrative agency's action was challenged. The agencies in question had no legislative authority. See Williams, at 218; Washington Fed'n of State Employees, at 145. Here the Council had legislative powers and was acting in that capacity. We also find that the Council properly exercised its legislative power to enact section 12(D).
The State of Washington has granted its cities the power to regulate and restrict the location and use of buildings and land for residential and other purposes. RCW 35.63.080. Ordinances enacted by cities pursuant to this authority will be upheld as valid exercises of police power if they promote the public health, safety or welfare, and bear a reasonable and substantial relation to accomplishing the purpose pursued. Duckworth v. Bonney Lk., 91 Wn.2d 19, 26-27, 586 P.2d 860 (1978).
The court must determine the public purpose and the relationship of the legislation to it. Duckworth, at 27. If the court can reasonably conceive of facts warranting the legislation, those facts will be presumed to exist. The court will also presume that the legislation was passed with reference to those facts. Duckworth, at 27. Once the court has established that a substantial relation exists between a city's ordinance and the public health, safety and welfare, it may overturn the city's exercise of legislative authority only for arbitrary and capricious conduct. Duckworth, at 34; Lutz v. Longview, 83 Wn.2d 566, 574-75, 520 P.2d 1374 (1974). The burden of proof rests on the challenging party, not on the city. Duckworth, at 34.
Applying the tests and presumptions used in the Duck-worth case to the evidence presented here, this court finds that the Council intended to promote the public interest in preserving certain classes of housing in light of' development through enacting the new ordinance. The Council