The acts authorized herein are declared to be strictly for the public purposes of the municipalities authorized to perform same. Any municipality as defined in RCW 67.28.080 shall have the power to acquire by condemnation and purchase any lands and property rights, both within and without its boundaries, which are necessary to carry out the purposes of this chapter. Such right of eminent domain shall be exercised by the legislative body of each such municipality in the manner provided by applicable general law or under chapter 8.12 RCW.