Due to increasing urban and municipal competition for a limited water supply, declining ground water, and recurring drought, there is a need to develop sustainable cropping practices in the US Great Plains that consume less water. Alfalfa (Medicago sativa L.) is an important crop is most of this region and will likely remain an important part of cropping systems as water supply declines. This paper will combine the results of a scientific literature review of plant water relations for alfalfa and the results of a field trial that evaluates partial season irrigation strategies for alfalfa in Colorado. Studies conducted across the Great Plains and Inter-Mountain West of the United States over the past forty years have consistently found a linear relationship between consumptive water use and above ground biomass production for alfalfa across the range of geographic and climatic regions studied, with an approximate slope of 0.12 Mg ha-1 cm-1. Variability in this relationship may be explained due to differences temperature, stand age, timing of harvest, average daily solar radiation, the average daily vapor pressure, seasonal accumulation of growing degree-days, or variety of alfalfa. The partial season irrigation study compares biomass production, water use, and crop physiological characteristics for four distinct irrigation treatments. The treatments range from full irrigation to a treatment that limits irrigation to the period before the first alfalfa harvest. Results illustrate that irrigation water use efficiency can be improved through the practice of partial season irrigation.