The state water commission, after consulting with the northwest area water supply authority, shall establish the payments for water service to be paid by water user entities for purchase of water from the northwest area water supply project. The payments for water service must include each water user entity’s proportionate share of the operation, maintenance, and replacement costs, and also include a component for payment for capital costs. The commission shall include in its determination of each water user entity’s share of operation, maintenance, and replacement costs an amount to be deposited in the northwest area water supply project reserve fund for replacement, as established by section 61-24.6-07, for replacement and extraordinary maintenance of northwest area water supply project works. The amount of the reserve fund for replacement must be determined by the commission.