Wash. Rev. Code § 85.24.010
Whenever a portion of two or more counties require diking, drainage, or the erection of flood dams or drift barriers to prevent inundations, such portion of two or more counties may be organized into a district; and the board of commissioners, hereinafter provided for, shall have and possess the powers herein conferred, or that may hereafter be conferred by law upon such districts and board of commissioners, and all such powers not in conflict with those herein granted, which now exist under the provisions of the laws of the state relating to the establishment, construction and maintenance of dikes and drains; and such districts shall be known and designated as "Diking and Drainage District No. . . . . in . . . . . . and . . . . . . counties (here insert name of counties), of the state of Washington"; and shall have the right to sue and be sued by, in the name of its board of commissioners herein provided for, and shall have perpetual succession, and shall adopt and use a seal.
RCW 85.24.010