Irrigation in the Pacific Northwest

Historic Average Water Needs Estimate.
Using Constant Days of Year.

Uses Crop Coeffcients at 21 Predefined Days of Year, and Linear Interpolation for the Chosen Crop. Crop development dates are for Eastern Washington. The vastly different climate zones across Washington means that these dates are often different (planting and harvesting for example). You might try crop coefficient curves based on growing degree days (GDD) instead. Go here for more information.

Select Crop:Irrigation Efficiency
Select Station:


WSU Prosser - IAREC, 24106 N Bunn Rd, Prosser WA 99350-8694, 509-786-2226,