No, this is not permitted under the "Washington Housing Policy Act" (WHPA), RCW 35A.63.240.

This statute provides:

No city may enact or maintain an ordinance, development regulation, zoning regulation or official control, policy, or administrative practice which treats a residential structure occupied by persons with handicaps differently than a similar residential structure occupied by a family or other unrelated individuals. As used in this section, "handicaps" are as defined in the federal fair housing amendments act of 1988 (42 U.S.C. Sec. 3602).

Accordingly, a development regulation that requires a conditional use permit for a group home for handicapped or disabled individuals but not for single-family residences violates this statute, which is stricter than comparable provisions of the federal Fair Housing Act. In Sunderland Family Treatment Services v Pasco, 107 Wn. App. 109 (2001), the state court of appeals struck down Pasco's requirement that "group care facilities" obtain a special use permit:

[W]e conclude that the City violated the WHPA by defining "family" in such a way as to impose additional burdens on residential care facilities for the handicapped. The City violated the WHPA by adopting a regulatory scheme that permitted a "family" to obtain immediate occupancy of a residential structure but required "group care facilities" to obtain a SUP before occupying a similar residential structure. But for the City's definition of family, the residents of the proposed facility would have been entitled to immediate occupancy of the home. Instead, the residents of the proposed facility were denied access based on their handicap and familial status.

See also: "Group Homes: Local Control and Regulation Versus Federal and State Fair Housing Laws," by Ted H. Gathe, Washington State Bar Association Land Use Conference, May 1997 (Reprinted with permission of the author and the Washington State Bar Association).