State of Montana Dept. of Environmental Quality 2011 Helena, MT Montana State Library https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Geodatabases/mt_1981-2010_AveAnnPrecip.zip An accurate estimate of average annual precipitation (AAP) is a necessity for completing hydrologic analysis, developing stream flow statistics, or doing other related water resource planning. Consequently, tools to develop and complete such analysis are required. Endeavors should be automated, capable of very quickly updating AAP information as it become available, and available for widespread use without proprietary requirements. To meet such a mandate, we developed a free-ware UNIX based tool called PMAP, which allows rapid AAP estimates through universal Kriging. A case study was implemented for the state of Montana using the 1981-2010 water-year averages and a 400 m elevation grid. While there are many geo-statistical techniques to choose from in completing such analysis, the strength in our work is not necessarily the method that we selected, but rather the data supporting it. We compiled AAP estimates for over 1,400 stations across the region including 1,100 stations in Montana, and 300 adjacent to the state, to assure compatibility along the border for the analysis which is the most detailed compilation we are aware of. We then proceeded to evaluate the data using a number of geostatistical analysis techniques. Electronic results were then compared to hand-drawn products to assure appropriate location of AAP isohyets. Isohyetal lines were set at 50 mm (2 inch) increments under 500 mm (20 inches) and 250 mm (10 inch) increments above 500 mm (20 inches). The1981-2010 AAP map (isohyets and grids) will be available through the Montana Natural Resource Information System (NRIS) web site electronically, and software will be made available from the Montana Department of Environmental Quality upon request. Hydrologic analysis, developing stream flow statistics, or doing other related water resource planning using the average annual precipitation distribution from Water Years 1981-2010 The 1981-2010 AAP map (isohyets and grids) is available from the Montana Natural Resource Information System (NRIS) and software is available from the Montana Department of Environmental Quality upon request (see contact information). Feature Classes within Geodatabase: 1. Basins: This feature class contains the complete HUC4 USGS hydrologic basins for Montana watershed. This includes the portions of HUCs (USA only) that extend outside Montana's state boundaries. 2. Canada_Basins: This feature class contains the Canadian hydrologic basins that border Montana. 3. Counties: This feature class contains the boundaries for Montana counties. 4. D3M8Cont: This feature class contains an accurate estimate of average annual precipitation (AAP) isohyets line contours that are necessary for completing hydrologic analysis, developing stream flow statistics, or doing other related water resource planning. This AAP (line) feature class was developed through universal Kriging using the 1981-2010 water-year averages and a 400 m elevation grid. AAP estimates were compiled for over 1,400 stations across the region including 1,100 stations in Montana, and 300 adjacent to the state, to assure compatibility along the border for the analysis: the most detailed compilation we are aware of. The data were then evaluated using a number of geostatistical analysis techniques. Electronic results were compared to hand-drawn products to assure appropriate location of AAP isohyets. Isohyetal lines were set at 50 mm (2 inch) increments under 500 mm (20 inches) and 250 mm (10 inch) increments above 500 mm (20 inches). 4. D3M8Grid: This feature class contains an accurate estimate of average annual precipitation (AAP) isohyets grids that are necessary for completing hydrologic analysis, developing stream flow statistics, or doing other related water resource planning. This AAP (grid) feature class was developed through universal Kriging using the 1981-2010 water-year averages and a 400 m elevation grid. AAP estimates were compiled for over 1,400 stations across the region including 1,100 stations in Montana, and 300 adjacent to the state, to assure compatibility along the border for the analysis: the most detailed compilation we are aware of. The data were then evaluated using a number of geostatistical analysis techniques. Electronic results were compared to hand-drawn products to assure appropriate location of AAP isohyets. Isohyetal grids were set at 50 mm (2 inch) increments under 500 mm (20 inches) and 250 mm (10 inch) increments above 500 mm (20 inches). 5. Montana: This feature class contains the state boundary for Montana. 6. Precipitation: This feature class contains the monitoring stations used for the precipitation distribution map. 1981 2010 -116.1 -104.0 49.0 44.25 ISO 19115 Topic Category climatologyMeteorologyAtmosphere precipitation rain rainfall weather climate Montana The creators of this map have used their best efforts in preparing it. It is not absolutely guaranteed to be error free. The State of Montana makes no warrantees, expressed or implied, including without limitation warrantees of merchantability or fitness for any particular purpose. No liability is accepted in any event for any damages, including accidental or consequential damages, lost of profits, costs of lost data or programming materials, or otherwise in connection with or arising out of the use of this map. The software used to derive this map may obtained upon request. The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time. Klyle Flynn Montana Department of Environmental Quality Water Quality Planning Bureau Hydrologist mailing address

PO Box 200901

Helena MT 59620-0901 406-444-5974 406-444-6836 kflynn@mt.gov 8:00-5:00 M-F Phillip E. Farnes, John Huddleston, Kyle Flynn 2011 Proceedings of the Annual Western Snow Conference 79th Annual Western Snow Conference Western Snow Conference Paper presented 79th Western Snow Conference April 18-21, 2011 Lake Tahoe/Stateline, NV http://www.westernsnowconference.org/sites/westernsnowconference.org/PDFs/2011Farnes.pdf State Plane Coordinate System 2500 45.0 49.0 -109.5 44.25 600000 0 meters North American Datum of 1983 Geodetic Reference System 80 6378137 298.25722 Montana State Library mailing address

PO Box 201800

Helena MT 59620-1800 406-444-5354 406-444-5354 Montana Relay 711 406-444-0266 geoinfo@mt.gov geoinfo@mt.gov Downloadable Data The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time. ESRI file geodatabase https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Geodatabases/mt_1981-2010_AveAnnPrecip.zip 20140320 20111005 Michael Pipp Montana Dept of Environmental Quality Water Quality Planning Bureau mailing address

PO Box 200901

Helena MT 59620-0901 406-444-7424 mpipp@mt.gov {3b8333a8-c938-4021-a5c5-acdfdd37e80c}