Wash. Rev. Code § 70.44.360
The plan of division authorized by RCW 70.44.350 shall include: Proposed names for the new districts; a description of the boundaries of the new districts, which boundaries shall follow insofar as reasonably possible the then-existing precinct boundaries and include all of the territory encompassed by the existing district; a division of all the assets of the existing district between the resulting new districts, including funds, rights, and property, both real and personal; the assumption of all the outstanding obligations of the existing district by the resulting new districts, including general obligation and revenue bonds, contracts, and any other liabilities or indebtedness; the establishing and constituting of new boards of three commissioners for each of the new districts, including fixing the boundaries of commissioner districts within such new districts following insofar as reasonably possible the then-existing precinct boundaries; and such other matters as the board of commissioners of the existing district may deem appropriate. Unless the plan of division provides otherwise, all the area and property of the existing district shall remain subject to the outstanding obligations of that district, and the boards of commissioners of the new districts shall make such levies or charges for services as may be necessary to pay such outstanding obligations in accordance with their terms from the sources originally pledged or otherwise liable for that purpose.
RCW 70.44.360