WSPC04476 - Laserfiche WebLink

Home Browse Search

. I I I I I . I I I I. I I I I I I I I 002108 Hydrosphere's Colorado River Model December 29, 1993 Page i5 provided by Hydrosphere assigns agricultural uses the highest priority, followed by municipal uses and exports, followed by minerals, then thermal power and finally coal gas and oil shale. This ordering reflects the general order of development of water rights in the states but does not accurately reflect recent conversions of senior agricultural rights to municipal uses. Rather than attempt to interpret state policy any further, we defer to the model user for more refinement of the within-state and within-use-type priorities. A special priority "threshold" allows the user to determine which water uses in the Upper Basin will be considered as "present perfected rights" (PPR's). In the event of a Compact call, each state's curtailment will be determined and applied in such a way that only administrable (non-PPR) uses will be curtailed. Curtailments of non-PPR uses will occur according to the priorities assigned by the user. Local shortages may occur to any depletion located on a tributary; in that event, shortfalls will occur according to the relative priorities on the tributary. In this version of the model, the Federal reservoirs in the Upper Basin are considered junior to consumptive uses. Future versions of the model may allow for adjustment of the Federal reservoir priorities if our customers express interest in such a modification. Priorities in the Lower Basin are handled differently than those in the Upper Basin because allocations to the most junior uses in the Lower Basin are governed largely by policies such as the shortage and surplus strategies. In Hydrosphere's Colorado River Model the Mexico delivery obligation is given the highest priority, followed by consumptive uses other than MWD-excess and CAP. Mohave and Havasu target storage are satisfied next, followed by CAP "shortage" deliveries (please refer to the discussion of CAP in the previous section). Water stored below the shortage elevation in Lake Mead has the next priority, followed by deliveries to CAP sufficient to meet its "scheduled" delivery. The next priority is Mead storage above the "shortage" level and below the flood control pool. Lowest priority is assigned to the MWD-excess and CAP-excess requests. Thus, only Lower Basin spills, flood control releases from Mead, and storage above the target levels of Mohave and Havasu are available to meet the last portion of the MWD-excess and CAP-excess requests. Deliveries to the excess requests are divided equally between the MWD and CAP until one or the other is fully satisfied, and then entirely to the user with remaining capacity (following Article II (B)(2) of the Supreme Court decree in Arizona vs. California). To summarize, the water allocation priorities in the Lower Basin are as follows: I. Mexico delivery 2. Lower Basin consumptive use except MWD-excess and CAP 3. Mohave and Havasu target storage 4. CAP "shortage" deliveries S. Mead "shortage" storage 6. CAP "scheduled" deliveries . 7. Mead storage above the "shortage" level and below the target level 8. CAP-excess and MWD-excess use 9. Storage above the target storage levels of each reservoir. The user will not be able to modify Lower Basin priorities, though depletion levels, target storage levels, the shortage elevation and flood control space requirements are all parameters which are modifiable. Previous analyses with the model have shown that even under the most severe drought observed in the approximately SOO-year tree ring trace, uses senior to CAP are not affected. However, those analyses assumed current operating policies Hydrosphere Resource Consultants 1002 Walnut Suite 200 Boulder, Colorado 80302