Mont. Code § 75-6-306
A public agency entering into an agreement pursuant to this part may appropriate funds and may sell, lease, give, or otherwise supply to the authority personnel or services for the operation of the authority as may be within its legal power to furnish. A public agency, whether or not a party to an agreement pursuant to this part, and a publicly or privately owned water distribution company may enter into contracts with an authority, created pursuant to this part, for the purchase of water from the authority or the sale of water to the authority, for the treatment of water by either party, and for the distribution or transmission of water by either party. The authority may enter into the contracts. A public agency, whether or not a party to an agreement pursuant to this part, and a publicly or privately owned wastewater transportation or treatment system may enter into contracts with an authority, created pursuant to this part, for the transportation and treatment of wastewater by either party. The authority may enter into the contracts, subject to the prior approval of the public service commission, if the privately owned wastewater transportation or treatment system is subject to the jurisdiction of the public service commission. However, if the public service commission has not acted on a proposed contract within 90 days of its filing, approval is considered to have been granted. A contract may include an agreement for the purchase of water not actually received or the treatment of wastewater not actually treated. A contract may not be for a period in excess of 40 years, but renewal options may be included in the contract. The obligations of a public agency under a contract must be payable solely from the revenue produced from the public agency's water or wastewater system, and the public service commission, in the case of a water system whose rates are subject to its jurisdiction, shall permit the water system to recover through its rates revenue sufficient to meet its obligations under the agreement.
§ 75-6-306, MCA