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It appears that the primary effect of the SSD was to clarify the goals of competing water uses on the Colorado River, particularly between consumptive and non-consumptive (or instream) uses and between the Upper and Lower Basins. As highlighted in the summary chapter of the SSD: "Existing operating rules ... favor consumptive water uses over such non-consumptive uses as hydroelectric power generation, environmental protection, salinity control, and recreation. The extent of this favoritism... is out of all proportion to what are, arguably, the public values involved." (Lord et al., 1995, p. 942). Three of the eight Advisory Council members interviewed found SSD principal investigators to be predisposed to protecting instream uses. In one case, an AC member recalled that the study helped him clarify the agenda of instream water use advocates. Furthermore, recommendations such as creation of a basin-wide commission and the establishment of interstate water banks had been previously suggested in other venues with limited positive reception from the basin states. With positions on these issues already established by groups represented in the AC, the SSD recommendations clarified different agendas - in the words of one AC member "we went in with stated positions on these issues, and study results weren't likely to change them". Timing The SSD study was published in 1995. Since this time, levels in Lakes Mead and Powell have been near capacity (Figure 2). 11 Together, these two reservoirs can hold more than three times the annual flow the of the Colorado River - when they're full, the concern for drought tends to be low. Rather than being focused on long- or short-term drought, the Colorado Basin states are currently preoccupied with allocating surplus water, driven by increasing demand rather than decreasing supply. Interviews across the three groups in Table 3 indicate that drought isn't a current concern in the Colorado Basin, let alone one that lasts nearly 20 years, and that the timing of SSD assessment seems to have prevented it from having a greater impact. If a severe-drought crisis had coincided with the publication of the study, the result may have been significantly different. Indeed, in "closing water systems" such as the Colorado, crisis appears to be necessary to promote recognition of interdependent uses and negotiation of agreements amongst basin states (Pulwarty and Melis, 2000). As discussed in the next section, the crisis of declining salmon populations in the Columbia River Basin has led to the consideration of alternative management approaches, including recognition of the ocean's role in salmon mortality, and the once-radical idea of dam removal. Given the lack of a crisis event in the Colorado Basin, it may be premature to evaluate the effectiveness of the SSD assessment, as its findings and recommendations could yet be used in future drought scenarios. Although the timing of SSD publication coincided with abundant water supply in the Colorado Basin, much of the West was in the grip of drought during the Advisory Council meetings in 1991 and 1992. During this time, water levels in Lake Powell were at their lowest since the initial filling of the reservoir and storage in Lake Mead dropped by nearly 4 million acre-feet compared to the wet years of the mid- 1980's (Figure 2). Both Arizona and California, for example, faced limits to surplus water from the Colorado River, and strict conservation programs were enacted in southern California and Las Vegas (Fradkin, 1995). Thus, discussion of long-term drought was quite timely, as the impacts of drought were occurring in the states represented by AC members. If timing was a primary determinant of the 8
ineffectiveness of the SSD, then it appears to require a drought more severe than the 1987-92 event to consider policy alternatives like those suggested in the SSD. Also, limited advertising of study results to the general public precluded the accumulation of political support necessary to make these policy changes. During the early 1990s, the AC members were apparently the only stakeholders intimately aware of both the ongoing drought event and the policy implications of the SSD. Choice of drought scenario Assessments of abrupt climate change are faced with the difficult task of addressing low probability, high impact events that adequately represent the range of climate variability in a region, while simultaneously steering clear of examples so extreme that nobody pays attention (i.e. that lack salience). For example, initial discussions with SSD principal investigators revealed some concern that the drought chosen for analysis was too extreme. In particular, the low probability of the event may have prevented the SSD from registering with stakeholders in the Colorado Basin. Further interviews, however, indicated that a minority of both the SSD investigators and AC members believed that the low probability of the drought prevented its full consideration by water managers. In most cases, interviewees felt that the occurrence of severe drought, even if only once in the last 500 years, was adequate justification to consider the implications of such an event for current and future water allocation policies. Thus, despite the limited precedence for analogous drought events, the SSD participants appear to have chosen an event that was salient to users in the region. The drought scenario used in the SSD assessment was based on water flows estimated using tree rings, but with the flows rearranged in time. The rearranged scenario was created by ordering annual values such that each year during the 20-year event had progressively lower flow (Tarboton, 1995). Although the total volume of Colorado River flow over the entire drought remained the same, the timing of the flows was altered to create an event even more extreme than that in the paleoclimatic record. Despite original intentions to determine the impacts associated with both scenarios, the re-arranged drought was the event on which the entire SSD assessment was based. This scenario was used to create a "worst case" contingency for testing the ability of the regional reservoirs and the Law of the River to cope with extreme, and perhaps unrealistic, drought. One of the groups which funded the study, the Metropolitan Water District of Southern California (MWD), doubted the credibility of the re-arranged scenario. Correspondence between the MWD and the study organizers indicate the MWD found the rearranged scenario to have no hydrological basis, and therefore should not have been used in the assessment. Referring to the rearranged drought, an engineer from MWD wrote to SSD organizers in 1994: "Considering its nature, it is possible that water resources managers will dismiss the findings, conclusions, and recommendations contained in the report due to the authors' choice of assumption for the representative drought." 12 The MWD repeatedly made attempts to comment on the SSD report, but most of them, including doubts about the re-arranged scenario, were left unaddressed. 13 This apparently is the result of both the linear nature of the assessment process and skepticism of Metropolitan's motivations. Although the SSD lasted for nearly 10 years, each stage of the project built on the previous stage - to make the major changes requested by MIND would have required that the study completely redone, an unrealistic request given funding constraints. Also, Metropolitan has serious reservations about the need for a basin-wide commission, because majority-based voting in such an arrangement could lead to reduced water supplies 9
Page 1 and 2: Belfer Center for Science & Interna
Page 3 and 4: FOREWORD This paper was written as
Page 5 and 6: INTRODUCTION BACKGROUND TABLE OF CO
Page 7 and 8: INTRODUCTION As the number and reso
Page 9 and 10: COLORADO BASIN WATER MANAGEMENT & P
Page 11 and 12: SEVERE-SUSTAINED DROUGHT ASSESSMENT
Page 13: period for the past 30 years, it is
Page 17 and 18: Although the SSD lasted several yea
Page 19 and 20: oceanic variability - constraints o
Page 21 and 22: legitimacy, and credibility. If an
Page 23 and 24: eservoir management would result in
Page 25 and 26: of the SSD, which seem quite reason
Page 27 and 28: Fisher-Vanden, K., Institutional po
Page 29 and 30: Sangoyomi, T. B., and Harding, B. L
Page 31 and 32: Table 4. Pacific Northwest Intervie
Page 35 and 36: ENDNOTES 1 Total allocation had rea
Page 37: 23 Based on formal written comments

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