Powers, authorities, or rights expressly or impliedly granted to any city, town, or county or their agents under any provision of RCW 35.21.730 through 35.21.755 shall not be operable or applicable, or have any effect beyond the limits of the incorporated area of any city or town implementing RCW 35.21.730 through 35.21.755, unless so provided by contract between the city and another city or county.