(1) Substantial credible information must be provided showing there is surface water physically available at the flow rate and volume that the applicant seeks to appropriate for the proposed period of diversion.

(2) If actual stream gaging records are available, they should be used to estimate the flow rates and volumes at the source of supply in the amount the applicant seeks to appropriate, the following is required:

(a) the medians  of the monthly average flow rates and volumes for the stream gaging station period of record during the proposed months of diversion; 

(b) a legible copy or excerpt of the data source, study or report(s) used in documenting water availability in the source of supply; and

(c) a description of all conclusions, calculations, data, and assumptions used in estimating water availability.

(3) If actual flow rate and volume data are not available to estimate the monthly median flows, then the applicant will need to use an accepted method for estimating surface water flow rates and volumes in conjunction with discharge measurements to validate the estimation technique used. Some accepted methods are listed in (6) .

(4) When stream flow gaging station data are not available and monthly median flow estimation techniques are used, the following stream discharge data must be collected:

(a) Stream flow measurements in cfs or gpm must be collected at least once every month during the proposed period of diversion at the most suitable location on the source of supply, and at or directly upstream of the proposed point of diversion. Measurements taken and submitted under this method must include:

(i) a legible copy of the actual flow measurements;

(ii)calculations used to establish flow rates in cfs or gpm;

(iii) the dates measurements were taken, with a description of current weather conditions;  Weather conditions include sky conditions, noting any rain and snow, approximate temperature, and approximate wind conditions, e.g., "partly cloudy, light wind, about 60 degrees" or "light rain, calm, about 65 degrees" or "clear, moderate wind, about 40 degrees".

(iv) the type of measuring device or method used; and

(v) a written legal land description or map clearly showing where the measurements were taken.

(5) If the application involves new storage of surface water such as a reservoir, pond or pit, or enlargement of a natural or manmade lake, the application must include the following information:

(a) that the source of supply has the volume of water physically available for the proposed beneficial use;

(b) information and data that show the amount of water to be stored is physically available during a median year and in the amount the applicant seeks to appropriate using the methods described in (2) and (3) ; and

(c) projected evaporation and seepage losses.

(6) The following reports may contain accepted methods for estimating surface water flow rates and volumes:

(a) "Methods for Estimating Monthly Stream Flow Characteristics at Ungaged Sites in Western Montana," USGS Open-file Report 89-40;

(b) "A Method for Estimating Mean and Low Flows of Streams in National Forests of Montana," USGS Water RESOURCES Investigation Report 85-4071;

(c) "Stream Flow Characteristics of Mountain Streams in Western Montana," USGS Open-File Report 84-244;

(d) "Estimated Monthly Percentile Discharges at Ungaged Sites in the UpperYellowstoneRiver Basin in Montana," USGS Water RESOURCES Investigation Report 86-4009;

(e) "A Method for Estimating Mean Annual Runoff of Ungaged Streams Based on Characteristics in Central and Eastern Montana," USGS Water RESOURCES Investigation Report 84-4143;

(f) "Estimates of Monthly Flow Characteristics at Selected Sites in the UpperMissouriRiver Basin, Montana, Base Period Water Years 1937 - 86," USGS Water RESOURCES Investigations Report 89-4082;

(g) "Mean Annual Runoff and Peak Flow Estimates Based on Channel Geometry of Streams in Southeastern MT," USGS Water RESOURCES Investigation Report 82-4092;

(h) "Mean Annual Runoff and Peak Flow Estimates Based on Channel Geometry of Streams in Northeast and Western Montana," USGS Water RESOURCES Investigation Report 83-4046; and

(i) "Estimates of Mean Monthly Stream Flow for Selected Sites in the MusselshellRiver Basin, Montana," USGS Water RESOURCES Investigation Report 89-4165.

(7) Other professionally documented hydrologic methods for estimating stream flow or annual runoff which may be applicable and acceptable to the department, including the Orsborn method, Mannings equation, U.S. natural RESOURCES AND CONSERVATION service-developed mean annual runoff data, and drainage area information paired to gaged streams in similar type basins may be acceptable. The department will determine the acceptability of other methods on a case-by-case basis.

(a) If one of these methods is used, the applicant must also include a brief description of the method used and assumptions and calculations used in estimating flow rates and volumes.