(1) The county legislative authority may provide for the payment of the whole or any portion of the cost and expense of any duly authorized road improvement by bonds and/or warrants of the improvement district which bonds shall be issued and sold as herein provided, but no bonds shall be issued in excess of the cost and expense of the project nor shall they be issued prior to twenty days after the thirty days allowed for the payment of assessments without penalty or interest.
(2) Notwithstanding subsection (1) of this section, such bonds and warrants may be issued and sold in accordance with chapter
39.46 RCW.