MunicipalDroughtRestrictionsInColorado

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KENNEY, KLEIN, AND CLARK result is based on only 12 days of voluntary restric- (Shaw and Maidment, 1987) of Austin, showed volun- tions. Only when expected use per capita is used to tart' restrictions to have no effect. However, Shaw et measure effectiveness are voluntary restrictions al.'s (1992) study of the 1991 Southern California shown to have significant value, yielding savings as drought found San Diego's voluntary program to yield high as 12 percent in one case (Fort Collins) and summer savings of 27 percent (compared to 36 per - savings of at least 7 percent in seven of the eight cent from Los Angeles' mandatory program). Thus, providers utilizing voluntary restrictions. while the track record of voluntary restrictions is somewhat spotty, it does seem safe to conclude that (3) The Greatest Savings (by percentage) Were mandatory restrictions generally work better than Found in the Cities With the Most Aggressive and voluntary restrictions, a central theme in the work of Stringent Mandatory Restrictions. The results during Lee (1981) and Lee and Warren (1981) regarding the mandatory restrictions indicate that the most strin- Iowa drought in 1977. Whether the generally greater gent limits on the frequency of outdoor watering. effectiveness of mandatory programs is worth the result in the greatest savings. Expected use per capita added political costs (compared to voluntary requests) during mandatory restrictions resulted in the follow - is, of course, a larger issue transcending. water man- ing reductions in water use: 22 percent for the four agement. water providers using every third day watering, 33 percent in the three cities limiting watering to twice a Utility of Expected Use Values. While the week, and 56 percent in Lafayette, which limited expected use formula employed in this study is, by watering to once a week. Measured in terms of actual modeling standards, relatively simple, it is nonethe- (measured) per capita use, these values are 17, 31, less .much more complicated and labor- intensive to and 55 percent, respectively. apply than approaches based solely on actual use. Whether this regression based technique should be (4) Every City Studied Was Able to Reduce Per adopted by water managers is an individual decision. Capita Use Over the Study Period Through the Use of Certainly large water providers with extensive in- Water Restrictions.. Savings ranged from a low of l house expertise and recordkeeping systems would percent in Thornton, the only city in the study that likely find this approach easier to apply than their did not use mandatory restrictions, to 49 percent in smaller counterparts. But the more relevant question Lafayette, the city with the most aggressive program: is whether the technique produces information that is of water restrictions.. Thornton enacted mandatory valuable to water managers. restrictions soon after the study period ended. Overall In this study, for most water providers and time savings in Thornton are a much more robust 9 per - periods studied, the expected use per capita savings cent when the per capita values are measured in was roughly about 2 to 6 percent greater than savings terms of expected use. While mandatory restrictions calculated from a traditional actual use per capita appear more effective than voluntary programs (Find- comparison with previous years. While this is not a ings 1 and 2) and stringent restrictions appear more large difference, it is nonetheless significant whenev- effective than less restrictive programs (Finding 3), er there is a management need to consider the all the conservation programs studied saved water. response of water users to climatic extremes, even in Doing something, therefore, appears better than inac- the absence of water shortages or water restrictions. tion. It is easy to imagine many scenarios where this type of information would be useful. Indeed, water man - The trends presented in Table 3 and described agers and planners spend a great deal of resources above were expected and generally reinforce findings understanding how drought and long term climate from similar investigations. For example, several changes can potentially influence supplies; a similar studies have shown mandatory water restrictions to investment of effort seems warranted in understand - be. effective when compared to expected use projec- ing the impact of climate on water demands. Incorpo- tions [e.g., Shaw et al. (1992) calculated summer sav- rating expected use calculations into the assessment ings in Los Angeles of 36 percent during the 1991 of drought response programs is only one of several drought; Shaw and Maidment (1988) calculated potential applications of this methodology, many of savings of 31 percent in Corpus Christi during the which are arguably more important than the specific 1984 drought; similarly, savings of 30 to 40 percent application featured in this study. were calculated in the San Francisco Bay area during the 1976 -1977 drought (CDWR, 1991)]. The literature Volumetric Savings. Another way to illustrate regarding voluntary water restrictions is less clear. the value of water restrictions — particularly the Shaw and Maidment's (1988) study of the Corpus mandatory restrictions — is in volumetric terms. This Christi drought in 1984, just like their earlier study is a particularly relevant measure of water savings JAWRA 84 JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION