Whenever in the judgment of the commissioners of any drainage district general benefits to the entire district will accrue therefrom, or the general plan for improvement as adopted by such district will be more fully or properly carried out thereby, the board of commissioners of such district is hereby given and granted authority and power to do the following things:

(1) Straighten, widen, deepen, improve, or alter the course of or discontinue the use and maintenance of, or abandon any existing drains or ditches in said district, and when abandoned or discontinued, the right-of-way may be held or disposed of by said district in the discretion of the commissioners;

(2) Dig or construct any additional and auxiliary drains or ditches therein;

(3) Obtain, improve, or alter any existing reservoirs, spillways or outlets;

(4) Lease, acquire, build, or construct additional, new, or better reservoirs, spillways, and outlets;

(5) Lease, acquire, erect, build, or construct and operate any pumping plant and acquire equipment necessary therefor;

(6) Divert, dam, or carry off the waters of any stream or water endangering or damaging said district and protect against damage or flood from any waters whatsoever; and

(7) Implement the provisions of a drainage maintenance plan adopted by the district.

PROVIDED, That in carrying out such powers, said commissioners shall not be authorized under RCW 85.06.640 through 85.06.700 to tap new sources of water which have other outlets and do not endanger the system or property of such district.