Utah State University Extension
In Utah, urban landscape irrigation accounts for 50-75% of the annual municipal water use, and much of it is applied in excess of the plant’s needs. This excess is a tremendous resource waste and the overspray causes substantial damage to hardscape (i.e., decks, patios, fountains, decorative concrete, etc.). Scheduling irrigation according to landscape plant water needs can reduce excess water use. In addition to conserving water, proper irrigation can encourage deeper root growth and healthier, more drought tolerant landscapes.
Cerny, Teresa A.; Kuhns, Mike; Kopp, Kelly L.; and Johnson, Mike, "Efficient Irrigation of Trees and Shrubs" (2002). All Current Publications. Paper 895.