WSP12678

• File Number: 8282.300
• Description: Lower Colorado River Administration
• Basin: Colorado Mainstem
• Date: 7/1/2000
• Author: USDOI/BOR
• Title: Calendar Year 1999 Compilation of Records in Accordance with Article V of the Decree of the Supreme Court of the United States in Arizona V. California Dated March 9, 1964
• Water Supply Pro - Doc Type: Data

The following tabulations for calendar year 1999 show final records of diversions of water
from the mainstream of the Colorado River, return flow of such water to the mainstream and
consumptive use of such water. The records were furnished by the u.s. Geological Survey,
International Boundary and Water commission, Bureau of Indian Affairs, Bureau of Reclamation
(Reclamation), National Park Service, u.S. Fish and wildlife Service, and water user
agencies. Diversions from the All-American Canal and Gila Gravity Main Canal at Imperial Dam
were assigned to each user by adding each user's proportional share of the total canal losses
to the delivery taken by each user at its turnout from the canal.

The tabulations show quantities of water drawn by surface diversion from the mainstream of
the Colorado River or pumped from the mainstream through pumps in mainstream and wells in the
Colorado River flood plain and the accounting surface. Diversions are listed in two separate
tabulations for each State. The first tabulation lists water users whose diversions are
measured and generally reported monthly. Return flows to the mainstream and consumptive use
are also listed for points of diversion and return when that information is available.

The second tabulation shows quantities of water pumped from wells in the flood plain of the
accounting surface where the amount of water use is generally determined from records of
power use. Amounts diverted by pumping were determined as follows: (l)for most electric
pumps, diversions were computed on a monthly basis from power records and a "kilowatt hour
per acre-foot factor" that was determined by discharge measurement; (2)for pumps other than
electric and some electric pumps, a consumptive use factor of 6 acre-feet per irrigated acre
of land per year was used.

Consumptive use estimated for individual diverters may be over or under estimated.
Reclamation is continuing the development of the Lower Colorado River Accounting system
(LCRAS) to refine estimates of consumptive use.

Tabulations for calendar year 1999 include determinations of the unmeasured Colorado River
return flows to Lake Mead from Las Vegas Wash which accrue to the State of Nevada and a
portion of the unmeasured return flows from the Yuma Mesa which are credited to the State of
Arizona.

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