United States Department of Agriculture
Natural Resources Conservation Service		 Montana Go to Accessibility Information
Skip to Page Content




Tables

Table 1.  Water Use Factor
Mean Annual Precipitation (Inches) Available Water-holding Capacity Total to 60 inches Design Level Needed Use Factor* Plant Species Use Group (Table 2)
Low Medium High
<10 All 1 6 10 16
10 - 14 <7.5 2 3 5 8
>7.5 2 1 3 5
14 -19 <3.75 2 2 4 7
3.75 - 7.5 3 1 2 3
>7.5 4 0 0 0
>19 <3.75 3 1 2 3
>3.75 4 0 0 0

* Use the next highest use factor and design level if persistent drought conditions or pro-longed above-average growing season temperatures are a concern.

 

Table 2.  Windbreak Species Root/Crown Widths
Water Use Consumptive Groups Typical With-in Row Spacing Between Tree/Shrub (ft.) Typical Root/Crown Width at 20 year (ft.)
High Use Group: Plains cottonwood, white poplar 12 25
Golden willow, purple willow, Siberian arborvitae 10 13
Redosier dogwood, centennial cotoneaster, Peking cotoneaster 4 6
Medium Use Group: Douglas-fir, Scotch pine, Black Hills spruce, Colorado blue spruce 12 10
Bur oak, green ash, common hackberry, honeylocust 10 11
Amur maple, Arnold hawthorn, Saskatoon serviceberry, Manchurian crabapple, Siberian crabapple, common chokecherry, black cherry 8 14
Late lilac, American plum, blueleaf honeysuckle, silverberry, Nanking cherry, Russian almond 5 8
Low Use Group: Siberian elm, limber pine, ponderosa pine 12 12
Golden currant, potentilla, woods rose, western sandcherry 4 6
Eastern redcedar, Rocky Mountain juniper 8 9
Caragana, silver buffaloberry, common lilac, skunkbush sumac, sea-buckthorn 6 7

NOTE:

  1.  “Typical With-in Row Spacing between Tree/Shrub” can help in the placement of emitters.
  2. The “Typical Root/Crown Width at 20 years” is not to be used for actual row-to-row spacing (the width indicates a root density factor for irrigation computations only).
Table 3. Climatic Area Factor
County Name Field Office Climatic Area* Climatic Area Factor County Name Field Office Climatic Area* Climatic Area Factor
Beaverhead Dillon 3 1 Madison Sheridan 4 0.94
Big Horn Hardin 1 1.27 Meager White Sulphur Springs 4 0.94
Blaine Chinook 2 1.12 Mineral Missoula 3 1
Broadwater Townsend 3 1 Missoula Missoula 3 1
Carbon Joliet 1 1.27 Musselshell Roundup 1 1.27
Carter Ekalaka 2 1.12 Park Livingston 3 1
Cascade Great Falls 2 1.12 Petroleum Winnett 2 1.12
Choteau Fort Benton 2 1.12 Phillips Malta 2 1.12
Custer Miles City 1 1.27 Pondera Conrad 4 0.94
Daniels Scobey 2 1.12 Powder River Broadus 2 1.12
Dawson Glendive 1 1.27 Powell Deer Lodge 4 0.94
Deerlodge Deer Lodge 5 0.81 Prairie Terry 1 1.27
Fallon Baker 2 1.12 Ravalli Hamilton 2 1.12
Fergus Lewistown 5 0.81 Richland Sidney 2 1.12
Flathead Kalispell 3 1 Roosevelt Culbertson 2 1.12
Gallatin Bozeman 4 0.94 Rosebud Forsyth 1 1.27
Garfield Jordan 1 1.27 Sanders Plains 2 1.12
Glacier Cut Bank 4 0.94 Sheridan Plentywood 3 1
Golden Valley Ryegate 3 1 Silverbow Whitehall 4 0.94
Granite Philipsburg 5 0.81 Stillwater Columbus 2 1.12
Hill Havre 2 1.12 Sweetgrass Big Timber 2 1.12
Jefferson Whitehall 3 1 Teton Choteau 4 0.94
Judith Basin Stanford 4 0.94 Toole Shelby 4 0.94
Lake Ronan 3 1 Treasure Hysham 1 1.27
Lewis & Clark Helena 3 1 Valley Glasgow 2 1.12
Liberty Chester 3 1 Wheatland Harlowton 4 0.94
Lincoln Eureka 3 1 Wibaux Wibaux 3 1
McCone Circle 2 1.12 Yellowstone Billings 1 1.27

* Source – Montana Irrigation Guide, Chapter 4 - Water Requirements, Figure 4.1 Irrigation Climatic Areas of Montana

< Back to Water Needs of Windbreaks for Trickle Irrigation System Design

Last Modified: 08/20/2008