1. (1) An appropriator proposing to temporarily lease a water right pursuant to 85-2-428, MCA, must file an application with the department. An application may be filed only by the owner of record of the water right proposed for lease.

2. (2) The applicant must provide evidence that the water right has been used within the five years prior to the date an application is filed. Evidence of use under this section includes, but is not limited to the following:

   1. (a) dated photographs or aerial imagery demonstrating use of water;
   2. (b) notarized affidavit(s);
   3. (c) power bills or other records that document pump usage if the conveyance system includes a pump;
   4. (d) water use measurement records, or
   5. (e) crop production records.

3. (3) If the department previously identified the historical consumptive use of the water right proposed for lease as part of an earlier change authorization, the department may reuse that calculation when reviewing an application for a temporary lease. If the historical consumptive use of the water right proposed for lease has not been calculated by the department through a previous change application, the department will use the following standards for estimating consumptive use of the water right when reviewing an application for temporary lease:

   1. (a) the consumptive volume for irrigation is the lesser of:

      1. (i) crop consumptive use as calculated using the methodology from ARM 36.12.1902(14) through 36.12.1902(16)(f). This methodology will use the priority date of the right being leased to determine the applicable county management factor; or
      2. (ii) 2.0 acre-feet per acre irrigated;
   2. (b) the consumptive volume for domestic or multiple domestic use is 10% of the assigned volume for the respective purpose;
   3. (c) the consumptive volume for lawn and garden, shrubbery, and shelterbelts is 1.75 acre-feet per acre per year based on 70 percent of 2.5 acre-feet per acre per year;
   4. (d) the consumptive volume for stockwater is 15 gallons per day or 0.017 acre-foot per year per animal unit based on ARM 36.12.115. Animal unit equivalencies for water consumption are set out in ARM 36.12.101 and the DNRC water calculation guide;
   5. (e) if a place of storage is being discontinued for the duration of the temporary lease, the consumptive use from evaporative losses as calculated based on ARM 36.12.116; and
   6. (f) other consumptive uses not covered in this section must be evaluated, calculated, and justified by the applicant. The evaluation must include an explanation of how the water is beneficially used for the purpose and how any wastewater or waste disposal occurs.

4. (4) An application must include a statement of potential adverse effects and description of the planned actions the applicant will take which demonstrate no adverse effect on other water rights.

   1. (a) The applicant's statement must explain what potential adverse effect could occur from the change in use under the temporary lease and how they made that determination.

   2. (b) The applicant's description of planned actions must document the effects to other water rights including the following:

      1. (i) the effect to water rights using the same point of diversion;
      2. (ii) the effect that ceased use of all or a portion of the leased water right at the place of use will have on other water users; and
      3. (iii) the effects of any changes to the historic diversion pattern including rate and timing.
5. (5) If storage is being temporarily added, the applicant must identify the capacity of the storage facility and how the capacity was calculated.
6. (6) At minimum, the department will identify and provide written notice to all owners of record of water rights, that according to the records of the department, may be affected by the proposed lease of water.

Authorizing statute(s): 85-2-113, MCA

Implementing statute(s): 85-2-428, MCA

History: NEW, 2025 MAR, Notice No. 2025-157, Eff. 10/1/25.