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<br />CAP ranks
<br />"ehind other
<br />".., .
<br />river users
<br />in dry years
<br />P' lanning for the Central Ari-
<br />zona Project includes esti.
<br />mating how much Colorado
<br />Rive.r, water the CAP will get in
<br />yelU'S of shortage - that is, any
<br />year in which Arizona cannot get
<br />ita full entitlement of 2.8 million
<br />acre-feet aCriver water.
<br />The CAP will get the river
<br />water after other Arizona users
<br />with better water rights get
<br />theirs.
<br />The U.S. Bureau of Reclama-
<br />tion, the chief planner, and the
<br />Arizona Department of Water
<br />ResoUlce& disagree about when 8
<br />shortage should be declared.
<br />And when a shortage does
<br />occur, they disagree about how
<br />muclt water the CAP should get.
<br />The bureau has proposed 400,-
<br />000 acre-feet of water in shortage.
<br />years; the water-resources agency
<br />suggested 700,000.
<br />_The purpose of declaring a
<br />shortage is twofold:
<br />. To ensure the generation of
<br />electricity at Hoover Dam, which
<br />impounds Lake Mead. Water
<br />discharged from the lake goes
<br />through the dam's powerhouse.
<br />. To ensure the maximum
<br />amount of water availability
<br />under the smallest Colorado
<br />River runoff.
<br />The disagreement about the
<br />amount of water that will be
<br />available and about when power
<br />generation would be threatened.
<br />centers on how rapidly the Upper
<br />Basin states use the water to
<br />which they are entitled.
<br />In the bureau's planning, it
<br />credits the Upper Basin states
<br />with using all of the water the
<br />bureau believes they ever will
<br />use. What the Upper Basin states
<br />dq not use will be available to the
<br />Lower Basin.
<br />Water unused by the Upper
<br />Basin will flow into Lake Mead,
<br />theiIPurce of water for the CAP.
<br />. Director Wealey E. Steiner of
<br />the:Water Resources Department
<br />said the bureau has overesti-
<br />mated Upper Basin water usage
<br />by about 700,000 acre. feet for the
<br />year 2035 and by higher amounts
<br />for earlier years. __~
<br />Steiner said the bureau is too
<br />cO'PSElrvative in its planning.
<br />Thomas G. Burbey, chief of
<br />CAP studies for the bureau's'
<br />Ari~ona projects office in Phoe-
<br />nix, agreed the bureau is cau-
<br />tious.
<br />He said the bureau, for study
<br />purJ>O:8es, assumes a water short-
<br />age"and would have the secretary
<br />of. ~ interior declare one when
<br />Lake Mead is less than half full,
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<br />to protect the minimum level in
<br />the lake at which water would be
<br />available for power generation.
<br />Mead is considered full when
<br />the water level is 1,229 feet above
<br />sea level, half full when it is 105
<br />feet lower, or 1,124 feet (see
<br />chart).
<br />Steiner agreed power genera.
<br />tion should be protected, but said
<br />his department's studies show
<br />that if Lake Mead is credited
<br />with the unused Upper Basin
<br />water, the lake would not fall
<br />j below the minimum level for
<br />producing electricity during the :
<br />CAP repayment period. That
<br />level is elevation 1,083 feet, an.
<br />additional 41 feet below the "half!
<br />full" level. -__J
<br />Burbey said tbat if Lake
<br />Mead's elevation should fall to'
<br />1,124 feet, it would mean runoff
<br />into the river had been below
<br />average for a number of years. :
<br />By having a shortage declared\
<br />automatically at 1,124 feet, the \
<br />
<br />bureau seeks to reduce the lake's
<br />discharges so by the end of the
<br />low~runoff years, its surface
<br />would not have fallen below the
<br />minimum level for producing
<br />electricity.
<br />Studies by both the bureau and
<br />the Water Resources Department
<br />are based on cycles of wet and
<br />. dry years for the Colorado River
<br />watershed since 1906.
<br />In the wettest years, approxi.,
<br />mately 24 million acre.feet of
<br />water flowed into the river; in the
<br />dryeat YIl!IBl', it Wll&- .~-,.G-mil-
<br />lion. The- average has been about'
<br />15 million.
<br />The bureau's studies - and
<br />there are 15 of them, each
<br />providing a different scenario for
<br />the amount of water that would
<br />be available - show shortages in
<br />as many as 36 years and 88 few as
<br />four during the first 50 years of
<br />CAP operation.
<br />The Water Resources Depart-
<br />ment foresees 11 or 12 years of
<br />shortage between now and the
<br />year 2035.
<br />Steiner objects to the bureau's
<br />plan for the immediate-shortage
<br />declaration because it could mean
<br />deliveries of CAP water would be
<br />reduced drastically from one year
<br />to the next.
<br />For example, if the CAP reo
<br />ceived 1.2 million acre-feet in the
<br />year 2005 and a shortage was
<br />declared, the CAP would get
<br />400,000 acre~feet in 2006.
<br />Steiner said the bureau should
<br />be more flexible so that when
<br />shortages appear to be coming,
<br />the amount of water delivered to
<br />the CAP can be reduced less
<br />abruptly.
<br />Before the CAP begins to take
<br />water from the river, the interior
<br />secretary will make the final
<br />decision about the river's man.
<br />agement based upon data pro.
<br />vided by the bureau, the Water i
<br />Resources Department and other:
<br />Colorado River states.
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