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<br />- COLORADO WATER
<br />
<br />June 1996
<br />
<br />WATER RESEARCH
<br />
<br />..
<br />
<br />SEVERE SUSTAINED DROUGHT
<br />Managing the Colorado River System
<br />in Times of Water Shortage
<br />
<br />by the Severe, Sustained Droughl Study Team
<br />
<br />This article summarizes a multidisciplinary study conducted by the Powell Consortium, an alliance of seven Wale,.
<br />Resources Research Instilutes and Centers from the slates of Arizona. California. Colorado. Nevada. New Mexico.
<br />Utah and Wyoming. The consortium wasfarmed /0 work on water resources problems of the Colorado RiverlGreol
<br />Basin region. The comp/ele reporl presents papers collected and published in a special issue (Oct, /995) oflhe
<br />American Water Resources Association's WATER RESOURCES BULLETIN Roberl A, Young. Professor of
<br />Agricultural and Resource Economics. Colorado Slole University, authored the publication's Introduction and
<br />Overview. William Lord was senior author of the Evaluation of Ins/flU/fonal Options discussed in this article. A
<br />complete list of sludy participants, in alphabetical order. can be found at the end of the article,
<br />
<br />The Colorado River is one of the most highly controlled river
<br />systems in the world, In most years, the flow of the river is so
<br />intensively utilized that there is no final discharge into the
<br />Gulf of California, its outlet to the sea, Today, the river
<br />provides part of the municipal water supply for 20 million
<br />people in seven states, for two million acres of fannland,
<br />generates 12 million kW of electricity a year, and provides
<br />habitats for fish, birds and wildlife, including a number of
<br />endangered species, Six national parks and recreation areas
<br />support a multimillion-dollar recreation industry of boating,
<br />hiking, fishing and whitewater rafting.
<br />
<br />Dividing up the Colorado River waters involved
<br />compromises, tradeoffs, interstate compacts, s U.S. Supreme
<br />Court decree, a treaty with Mexico and federallegislalion, An
<br />interstate compact was proposed in 1920, and a federal-state
<br />compact commission began negotiations in 1922. The
<br />commission divided the watershed into two basins - the
<br />Upper Colorado Basin (Colorado, New Mexico, Utah and
<br />Wyoming) and the Lower Colorado Basin (Arizona,
<br />California and Nevada). Of the river's then estimated 16.9
<br />million acre-feet, the commission apportioned 7.5 million
<br />acre-feet of consumptive uses to the upper basin and 7.5
<br />million acre-feet of uses to the lower basin, with an additional
<br />1 million acre-feet going to the lower basin states, if available,
<br />By 1944 treaty, Mexico receives 1.5 millien acre-feet, about
<br />one-tenth of the estimated average virgin flow. The existing
<br />complex of Colorado River water allocation and management
<br />rules is referred to as the "Law of the River."
<br />
<br />Additionally, Native Americans living along the Colorado
<br />River have, in many instances, claims on water that date back
<br />to the mid-1800s, They are often the senior owners of river ,
<br />rlO'htc:: '!:l...............rI:........ Ion r 1 C' ~upreme Court rulings.
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<br />Systematic river flow measurements in the Colorado River
<br />Basin, which began only a linle over a century ago. shO\l,.'
<br />considerable fluctuation in annual water supplies and include
<br />some intervals of persistent low flows, Instead of the 16,9
<br />million acre-feel estimated to be there for the dividing in the
<br />'205. [he river has been flowing at an observed mean rate of
<br />15,2 million acre-feet and during periods of drought has
<br />dropped as low as 9 million acre-feet a year,
<br />
<br />The US Bureau of Reclamation has constructed water storage
<br />facilities with a capacity of roughly four times the annual
<br />flows, \\'hich renders the issues of drought impact unimportant
<br />during normal climatic fluctuations. However, under extreme
<br />climatic conditions, drought management could become
<br />significant.
<br />
<br />Investigators from several Colorado River Basin states have
<br />been engaged for about a decade in a major program of
<br />research designed to evaluate the capability of the region's
<br />water management stroctures and institutions to cope with a
<br />severe sustained drought (SSD). Phase I of this research
<br />program included the following:
<br />
<br />. Tree ring reconstructions of historic rainfall conditions;
<br />
<br />. Hydrologic analyses of the probability distribution of
<br />river flows;
<br />
<br />. Engineering simulations of the functioning of the water
<br />management facilities and institutions under various
<br />runoff scenarios;
<br />
<br />Legal and other institutional analyses of current interstate
<br />water allocation rules, and possible changes in them;
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