Colorado River Compact
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The Colorado River Compact is a 1922 agreement among seven U.S. states in the basin of the Colorado River in the American Southwest governing the allocation of the river's water among the parties of the interstate compact. The agreement was signed at a meeting at Bishop's Lodge, near Santa Fe, New Mexico by representatives of the seven states.
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[edit] Provisions
The compact divides the river basin into two areas, the Upper Basin (comprising Colorado, New Mexico, Utah and Wyoming) and the Lower Basin (Nevada, Arizona and California). The compact requires the Upper Basin states to deliver water at a rate of 7.5 million acre feet per year (293 m³/s), averaged over a moving ten-year average. Based on historical rainfall patterns, the amount specified in the compact was assumed to allow a roughly equal division of water between the two regions. The states within each basin were required to divide their 7.4 million acre foot per year (289 m³/s) share allotment among themselves. The compact enabled the widespread irrigation of the Southwest, as well as the subsequent development of state and federal water works projects under the United States Bureau of Reclamation. Such projects included the Hoover Dam and Lake Powell.
The current specific annual allotments in the Lower Basin were established in 1928 as part of the Boulder Canyon Project. They are:
| Upper Basin, 7.5 million acre·ft/year (293 m³/s) total | |||
| Colorado | 51.75% | 3.88 million acre·ft/year (152 m³/s) | |
| Utah | 23.00% | 1.73 million acre·ft/year (68 m³/s) | |
| Wyoming | 14.00% | 1.05 million acre·ft/year (41 m³/s) | |
| New Mexico | 11.25% | 0.84 million acre·ft/year (33 m³/s) | |
| Arizona | 0.70% | 0.05 million acre·ft/year (2.0 m³/s) | |
| Lower Basin, 7.5 million acre·ft/year (293 m³/s) total | |||
| California | 58.70% | 4.40 million acre·ft/year (172 m³/s) | |
| Arizona | 37.30% | 2.80 million acre·ft/year (109 m³/s) | |
| Nevada | 4.00% | 0.30 million acre·ft/year (12 m³/s) | |
In addition to this, 1.5 million acre ft/year of Colorado River water is allocated to Mexico, pursuant to the treaty relating to the use of waters of the Colorado and Tijuana Rivers and of the Rio Grande, signed February 3, 1944, and its supplementary protocol signed November 14, 1944.[1]
[edit] History
The compact was the fruit of several years of negotiations among the states. The seven states had previously formed the League of the Southwest in 1917 to promote development along the river.[2] In 1921, Congress authorized the states to enter into a compact for allocation of the river resources. The agreement was approved by Congress in 1922, the same year it was signed. As part of the compact, the name of the river was standardized along its length. Previously the portion of the river upstream from its confluence with Green River had been known locally as the "Grand River". The change was opposed by many local residents in Utah and Colorado, and the new name was enforced locally by acts of the state legislatures in both states in the early 1920s.
The agreement was controversial even at the time, however. Arizona, for example, was dissatisfied with its allotment and refused to ratify the agreement until 1944 [1]. The specific allotments were disputed by Arizona until the United States Supreme Court upheld the amount in the 1963 decision in Arizona v. California. The agreement ended many years of dispute, clearing the way for the Central Arizona Project, authorized by Congress in 1968.
[edit] Criticism and renegotiation
In recent years, the compact has become the focus of even sharper criticism, in the wake of a protracted decrease in rainfall in the region. Specifically, the amount of water allocated was based on an expectation that the river's average flow was 16.4 million acre feet per year (641 m³/s). Subsequent tree ring studies, however, have concluded that the long-term average water flow of the Colorado is significantly less. Estimates have included 13.2 million acre feet per year (516 m³/s)[3], 13.5 million acre feet per year (528 m3/s)[4], and 14.3 million acre feet per year (559 m3/s)[5]. Many analysts have concluded that the compact was negotiated in a period of abnormally high rainfall, and that the recent drought in the region is in fact a return to historically typical patterns. The decrease in rainfall has led to widespread dropping of reservoir levels in the region, in particular at Lake Powell, created by the Glen Canyon Dam in 1963, where the exposure of long-inundated canyons has prompted calls for the deliberate permanent extinction of the reservoir.
In December, 2007, a set of interim guidelines on how to allocate Colorado River water in the event of shortages was signed by the Secretary of the Interior[6][7]. The guidelines are described as interim because they extend through 2026, and are intended to allow the system operators to gain experience with low-reservoir conditions while the effect of climate change on the Colorado River flow is further evaluated.[8] The agreement specifies three levels of shortage conditions, depending on the level of Lake Mead. When the surface elevation at Lake Mead is below 1,075 feet (relative to mean sea level) but above 1,050 feet, the Lower Basin states will receive 7.167 million acre feet per year (4.4 million acre feet to California, 2.48 million acre feet to Arizona, and 0.287 million acre feet to Nevada). When the surface elevation of Lake Mead is below 1,050 feet but above 1,025 feet, 7.083 million acre feet per year will be delivered to the Lower Basin states (4.4 million acre feet for California, 2.4 million acre feet for Arizona, and 0.283 million acre feet for Nevada). The most severe shortage considered in the interim guidelines is when the level of Lake Mead drops below 1,025 feet, in which event 7.0 million acre feet per year will be delivered to the Lower Basin states (4.4 million acre feet to California, 2.32 million acre feet to Arizona, and 0.280 million acre feet to Nevada).
[edit] References
- ^ Colorado River interim guidelines for Lower Basin shortages and the coordinated operations for Lake Powell and lake Mead, U.S. Bureau of Reclamation, December, 2007
- ^ Eric I. Boime, “Fluid Boundaries: Southern California, Baja California, and the Conflict over the Colorado River, 1848-1944,” (Ph.D diss. University of California, San Diego, 2002)
- ^ H. G. Hidalgo, T. C. Piechota, and J. A. Dracup, 2000: Alternative principal components regression procedures for dentrohydrological reconstructions, Water Resources Research v. 36, p. 3241-3249
- ^ C. W. Stockton and G. C. Jacoby, 1976: Long-term surface-water supply and streamflow trends in the Upper Colorado River Basin. Lake Powell Res. Proj. Bulletin no 18, National Science Foundation, Arlington, VA
- ^ C. A. Woodhouse, S. T. Gray, and D. M. Meko, 2005: Updated streamflow reconstructions for the Upper Colorado River Basin, Water Resrouces Research v. 42, W05415, doi:10.1029/2005/WR004455, 2006
- ^ Western States to Share Colorado River Water, National Public Radio, 14 Dec 2007.
- ^ Colorado River interim guidelines for Lower Basin shortages and the coordinated operations for Lake Powell and lake Mead, U.S. Bureau of Reclamation, December, 2007
- ^ U.S. Bureau of Reclamation Final Environmental Impact Statement: Colorado River Interim guidelines for Lower Basin shortages and coordinated operations for Lake Powell and Lake Mead, October, 2007. Chapter 4, page 15.
- Lawrence J. MacDonnell et al. (October 1995). "The Law of the Colorado River: Coping with Severe Sustained Drought". Water Resources Bulletin 31: 825-836.
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