Maintaining urban landscape health and services on reduced irrigation: a multi-site study in best management practices

Abstract

Urban landscapes in summer-dry climates face challenges to survival in the face of increasing water-use restrictions. Stringent regulations designed to reduce water use and waste have been established in much of the western/southwestern US due to ever-increasing populations and predictably cyclical droughts. To address this issue in California, the state Department of Water Resources collaborated with University of California researchers and a consulting landscape management contractor to implement conservation measures and best management practices (BMPs) in established urban landscapes across the state to see if these steps were sufficient to maintain acceptable plant health at a targeted water reduction level. Thirty sites in six distinct climate regions, that included parks, universities, private grounds, business parks, and golf courses were initially evaluated for irrigation system status, plant mix, and maintenance practices. BMPs were implemented: irrigation system repairs with improvements and optimization based on initial audit; irrigation scheduling based on climate, microclimate, planting density and species mix; application of organic mulch; and proper fertilization. Site personnel were given guidelines to maintain the BMPs over the period of two years. During this time, periodic observations were made on plant health, and follow-up audits were conducted on irrigation systems. Twenty-one of the 30 sites significantly reduced water use and waste the second year of the project compared to the first year by implementing the BMPs. In the hotter regions, some of the turfgrass areas saw a decline in health at the reduced water level, but shrubs maintained good health and performance at all sites. Failures to meet the reduction goals were generally due to lapses in following the BMPs or system failures that went unnoticed and therefore uncorrected by on-site maintenance personnel. Some sites realized a 50% or more reduction in water use without compromising plant health and accompanying ecosystem services.