In the event it shall be necessary for the public health, safety or welfare to undertake a project within a portion of a water management district which will benefit only 1 or more contiguous public corporations within the water management district, a petition may be filed with the secretary of the commission, signed by 1 or more of the public corporations which will be benefited by the project for the creation of a subdistrict to undertake such project. The petition shall be in conformity with the requirements of petitions for the creation of water management districts insofar as such requirements are applicable thereto. No commission or board shall be created for any subdistrict, but the commission and board of the water management district shall serve in such capacity with respect to the subdistrict. The commission shall determine whether or not it desires to undertake the project before any further action is taken thereon. If the commission shall determine to undertake the project, the commission and board shall proceed to adoption of an official plan and final order of apportionment in the same manner as provided in this chapter in the case of district projects: Provided, That in all actions of the commission involving the subdistrict, other than the determination aforesaid, only members of the commission from public corporations comprising the subdistrict shall be entitled to vote and the vote of a majority of such members shall control. The cost of the project within the subdistrict shall be assessed only against public corporations comprising the subdistrict, but may be financed as a part of the cost of other projects within the water management district. Except as herein otherwise provided all provisions of this chapter pertaining to projects in water management districts shall pertain to projects in subdistricts insofar as applicable thereto.