(b) The water resources commission shall cause a public hearing to be held on the watershed work plan in accordance with the provisions and procedures provided by section four hundred fifty-one of the conservation law in respect to public hearings on water supply applications. The commission shall with all convenient speed and within ninety days after the final hearing either approve, disapprove or modify the watershed work plan. In reaching its decision, it shall be the duty of the commission to review the watershed work plan and other data and the evidence taken at the hearing, with due regard being given to the allocation of the water resources of the state to the various interests desiring to utilize such resources for the general benefit of the public. In approving the watershed work plan as submitted, or as modified by the commission, the commission shall determine that the watershed work plan includes the necessary works of improvement and that the proposed works of improvement, will have no adverse effect on the general and equitable uses of the water resources of the state in areas which might be affected thereby.

(c) After approval by the commission, the watershed work plan as submitted or as modified, shall be the final complete watershed work plan for the project. The watershed work plan shall set forth the general scope and intent of the project but not necessarily include maps, plans and specifications in sufficient detail for contracting for and the construction of the works of improvement. 4. None of the works of improvement included in the final watershed work plan shall be undertaken or constructed or put into operation until detailed maps, plans and specifications therefor have been submitted to the commission for approval. The commission need not hold a public hearing on such an application but may call upon the watershed district or its administrative head or body to furnish such further information or proof as the commission may require. The commission shall determine whether the detailed maps, plans and specifications provide for the proper and safe construction of all work connected with the project. The commission may approve or disapprove the detailed maps, plans and specifications, or modify them and, as so modified, approve them. When approved or modified and approved, the detailed maps, plans and specifications shall be the final construction plan. 5. Modifications. Should it subsequently become necessary or desirable at any time either before or after the formation of a watershed district or the construction and completion of a project that the watershed work plan be modified in a substantial manner in scope or intent as specified in this subdivision five, or that the final construction plan be modified in a substantial manner, such modifications must be submitted to the board of supervisors and, if approved by the board, to the commission for such further action or approval as it may deem necessary or advisable before such modifications are put into effect. A change in scope or intent requiring modification of the watershed work plan and the action and approval prescribed by this subdivision five shall mean (1) a change in the multi-purposes and features of the project, or (2) a change affecting flood water storage which requires approval of committees of the Congress of the United States under the provisions of the "Watershed Protection and Flood Prevention Act". 6. Hearing expenses. The expenses of any hearing and determination required to be held and made by the commission shall be a charge against the county or counties and such county or counties shall, upon certification by the commission, pay such expenses to the persons entitled thereto.