Evaluating the effectiveness of water restrictions: a case study from Southeast Florida

One of the most commonly employed water conservation strategies is to restrict lawn watering to limited times on specified days. Water managers typically assume that limiting the frequency and duration of lawn watering will reduce water use. Consequently, the effectiveness of water restrictions is often evaluated based on observed compliance to the specified schedule, whether or not actual reductions in water use are achieved. This assessment approach is more practical than quantifying the reduction in water use brought about by restrictions because quantification of lawn water use is hampered by difficulties in disaggregating the various components of residential water use. Dual meters to separately meter the portion of public supply devoted to lawn water use are rare, and for households that withdraw water from private wells, canals, or ponds for lawn watering, there is no record of such water use at all. As a consequence of this gap in water use data, compliance to a prescribed frequency of watering is often equated with effectiveness. In this paper we develop an alternative metric for evaluating the effectiveness of water restrictions and present a case study in a suburban area in Southeast Florida that illustrates some of the challenges of quantifying lawn water use and explores some of the limitations of day of the week water restrictions as a conservation strategy.