WSP12637

• File Number: 8282.300
• Description: Colorado River Operations and Accounting - Lower Basin Administrative Procedures
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/1/1996
• Author: DOI-BOR
• Title: Description and Assessment of Operations-Maintenance and Sensitive Species of the Lower Colorado River - Volume I - Report - 08-01-96
• Water Supply Pro - Doc Type: Report/Study

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OJ23.33

. Reasonable consumptive use requirements of mainstream water users in the lower
basin,

· Net river losses,

· Net reservoir losses,

· Regulatory wastes,

. Requests for water by holders of water delivery contracts within the United States,
and of other rights recognized in the Court decree,

. Actual and forecast quantities of active storage in Lake Mead and the upper basin
storage reservoirs, and

. Estimated net inflow to Lake Mead.

Pursuant to the decree, water in excess of 7.5 maf consumptive use is apportioned 50 percent
to California, 46 percent to Arizona, and 4 percent to Nevada. If a State will not use all of
its apportioned water for the year, the Secretary may allow the other States to use the unused
apportionment in that year, as outlined in Section II(B)(6) of the Court decree. Unused
apportionment means Colorado River water within a lower basin State's basic or surplus
apportionment, or both, which is not put to beneficial consumptive use in that year within
that State. The decree in Section 1I(B)(6) specifically says that a right to the recurrent use of
unused apportionment cannot accrue by reason of the use thereof. The unused apportionment
water can be used when declared available by the Secretary; the use must be provided for by
a contract with the Secretary and must be considered a beneficial use. Unused apportionment
water may be withdrawn, subject to a 3D-day written notice.

The Secretary also has the discretion to determine if the system conditions warrant supplying
less than 7.5 maf for consumptive use, referred to as a shortage; a shortage has never been
declared and is not expected within the next 5 years.

4. Delivery to Mexico at the Northerly International Boundary (NIB)

The minimum and maximum water flow rates (average monthly flow rates in cfs) at the NIB
are the sum of the minimum and maximum flow rates specified in the Mexican Water Treaty
of 1944:

. Article 15 Schedule 1 (delivery of 1., 125,000 acre-feet annually in the Limitrophe
section of the Colorado River), and

. Schedule 2 (delivery of 375,000 acre-feet annually at the boundary line by means of
the All-American Canal); found on pages 30, 31, and 32 of the Mexican Water
Treaty.

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