The department of transportation shall construct and maintain recreational vehicle sanitary disposal systems in the following safety rest areas lying along highways which are a part of the interstate highway system:

(1) Gee Creek safety rest area, northbound and southbound on Interstate 5 in Clark county;

(2) SeaTac safety rest area, northbound on Interstate 5 in King county;

(3) Silver Lake safety rest area, southbound on Interstate 5 in Snohomish county;

(4) Winchester Wasteway safety rest area, eastbound and westbound on Interstate 90 in Grant county;

(5) Sprague safety rest area, eastbound on Interstate 90 in Lincoln county;

(6) Selah Creek safety rest area, northbound and southbound on Interstate 82 in Yakima county;

(7) Indian John Hill safety rest area, eastbound and westbound on Interstate 90 in Kittitas county;

(8) Smokey Point safety rest area, northbound and southbound on Interstate 5 in Snohomish county;

(9) Schrag safety rest area, westbound on Interstate 90 in Adams county.

Effective date—1980 c 60: "This act shall take effect July 1, 1980." [ 1980 c 60 s 4.]