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USE AND EFFECTIVENESS OF MUNICIPAL WATER RESTRICTIONS DURING DROUGHT IN COLORADO
<br />each of the eight providers studied is physically locat-
<br />ed in the South Platte basin and has some access to
<br />local supplies, the level of access is far from uniform.
<br />The South Platte water rights of some cities, particu-
<br />larly Denver, are much more extensive and senior
<br />than those of the younger suburbs such as Aurora and
<br />Thornton. Additionally, access to other sources, par-
<br />ticularly western slope (i.e., Upper Colorado River)
<br />resources, is far from uniform, based on water rights,
<br />engineering systems, and physical geography. Munic-
<br />ipalities without extensive or diversified sources were
<br />particularly vulnerable. Lafayette, for example, is pri-
<br />marily dependent upon a single watershed that by
<br />May 31 held only 13 percent of normal snowpack
<br />(NRCS, 2002b).
<br />Entering the summer of 2002, most cities along the
<br />northern Front Range had sufficient water in storage
<br />to satisfy normal levels of summer demand. With the
<br />notable exception of Lafayette, the real fear was not
<br />so much shortages in 2002, but rather the prospect of
<br />entering 2003 with depleted reservoirs combined with
<br />the possibility of another winter of low snowfall. For
<br />this reason, the water restrictions imposed in 2002
<br />were largely precautionary, with the level of restric-
<br />tions and the intensity of their enforcement reflecting
<br />the perceived risk of each municipality.
<br />Overview of Water Restrictions
<br />Our study period extended from May 1 to August
<br />31, 2002, the four months with the highest evapotran-
<br />spiration and highest lawn watering demand in Col-
<br />orado (Swift, 1996). During this period, five of the
<br />eight municipal water providers studied implemented
<br />voluntary restrictions on outdoor water use, with four
<br />eventually shifting to mandatory outdoor water
<br />restrictions. The remaining three cities used manda-
<br />tory programs exclusively. These programs were high-
<br />ly publicized by the local media, were prominently
<br />featured in city web pages, and in many cases were
<br />described in detail in mailings (sometimes included
<br />with monthly water bills) sent directly to the affected
<br />households. Public education was a part of all efforts.
<br />The key provisions of each program were the rules
<br />regarding lawn watering, although a mix of other con-
<br />servation elements were typically bundled with the
<br />watering restrictions. Four of the eight providers lim-
<br />ited lawn watering to once every three days, three
<br />cities limited watering to twice a week, while
<br />Lafayette restricted lawn watering to once a week.
<br />These restrictions often specified the time of day
<br />watering was to occur, the maximum length of the
<br />watering period, special rules for irrigating trees and
<br />perennials, and allowances for hand watering. Other
<br />common restrictions included prohibitions against
<br />using hoses to wash paved areas, limits on car wash-
<br />ing and filling or refilling swimming pools, and
<br />restrictions on planting and/or watering new sod.
<br />New drought inspired pricing mechanisms were also
<br />implemented in two cities during the study period to
<br />discourage and penalize excessive use. This informa-
<br />tion is summarized in Table 2, with the cities listed in
<br />increasing order of water restriction stringency.
<br />EFFECTIVENESS OF DROUGHT INSPIRED
<br />WATER RESTRICTIONS
<br />Two general strategies are used to measure the
<br />effectiveness of drought restrictions. The first
<br />approach is to compare daily water use (i.e., deliver-
<br />ies) during periods of water restrictions to water use
<br />over the same time periods in previous years. The sec-
<br />ond approach is to compare daily water use during
<br />drought restrictions to an estimate of what use would
<br />have been, given the temperature and precipitation
<br />conditions (i.e., "expected use "), in the absence of
<br />restrictions. The first approach, used extensively by
<br />the water providers, has the advantage of requiring
<br />only information that is readily available to the utili-
<br />ties. Additionally, the results are unquestionably rele-
<br />vant: the amount of water actually demanded (and
<br />thus delivered) is ultimately the figure most relevant
<br />to system operators. Finally, this approach has the
<br />advantage of being the traditional standard familiar
<br />to water managers as well as the public and policy
<br />makers.
<br />The second approach is considerably more compli-
<br />cated and therefore is used and publicized less fre-
<br />quently by the cities. Nonetheless, an approach
<br />accounting for expected use has the potential to offer
<br />a much more accurate assessment of drought restric-
<br />tion effectiveness. The reason is simple: in a year of
<br />extreme drought; it is a poor assumption that water
<br />use, in the absence of restrictions, will be similar to
<br />that seen in preceding years. To the contrary, drought
<br />conditions inevitably increase water demands, espe-
<br />cially for landscaping purposes, and failure to consid-
<br />er this impact can result in an underestimation of the
<br />effectiveness of drought restrictions. Similarly, on the
<br />odd chance that a drought restriction is enacted dur-
<br />ing a sudden easing of drought conditions, failure to
<br />compare observed use to an expected value can over-
<br />state the effectiveness of restrictions. This phe-
<br />nomenon was documented by Anderson et al. (1980)
<br />in their study of the Fort Collins drought in 1977.
<br />In this study, both approaches are used to assess
<br />the effectiveness of water restrictions.
<br />JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 79 1 JAWRA
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