Mont. Code Ann. § 85-5-201

(1) Each water commissioner appointed by the judge of the district court for the purpose of distributing water has the authority to determine the appropriate quantity and distribute to the parties interested, under a decree, permit, certificate, or change in appropriation right, the water to which those who are parties to the decree or holders of a permit, certificate, or change in appropriation right, or privy to a permit, certificate, or change in appropriation right, are entitled, according to their priority as established by the decree, permit, certificate, or change in appropriation right.

(2) The water commissioner may incur necessary expenses in the making of headgates or dams for the distribution of the waters if the parties fail or refuse to do so. Expenses associated with making headgates or dams for the distribution of water must be assessed against and paid by the party or parties for whom the ditch or ditches were repaired or the dams or headgates were made. In the discretion of the court, the costs or expenses may be assessed against the land upon which or for the benefit of which the expense had been incurred.

(3) (a) At the district court's discretion, a water commissioner may bill water users prior to the beginning of a distribution season for the purpose of offsetting costs associated with distributing water and water commissioner duties by submitting the information necessary for the billing to the clerk of the district court. A billing issued prior to the beginning of a distribution season:

(i) must be assessed on a per-user basis;

(ii) must be based on the report provided for in 85-5-107 for the prior year; and

(iii) may not exceed 80% of the amount that was provided to the district court pursuant to 85-5-107 for the prior distribution season on a per-user basis.

(b) Upon receipt of the information from the water commissioner, the clerk of district court shall proceed as provided in 85-5-204.

Distribution of water and related expenses

Every water commissioner appointed by the judge of the district court for that purpose shall have the authority to admeasure and distribute to the parties interested, under such decree, permit, or certificate, the water to which those who are parties to the decree or holders of a permit or certificate, or privy thereto, are entitled, according to their priority as established by the decree, permit, or certificate. The water commissioner, in case the parties fail or refuse to do so, may incur necessary expenses in the making of headgates or dams for the distribution of the waters. Such expense shall be assessed against and paid by the party or parties for whom such services in the repair of the ditch or ditches and the making of any dams or headgates were necessary. In the discretion of the court, such costs or expenses may be assessed against the land upon which or for the benefit of which such expense had been incurred.