WSP11307

• File Number: 8200.300.10.A
• Description: Colorado River Basin Legislation/Law - Interstate Water Transfers
• Basin: Colorado Mainstem
• Date: 12/1/1997
• Author: USDOI/BOR
• Title: Draft: Programmatic Environmental Assessment for Proposed Rule Making for Offstream Storage of Colorado River Water and Interstate Redemption of Storage Credits in the Lower Division States
• Water Supply Pro - Doc Type: Publication

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Off stream storage credits will be redeemed through forbearance of use in the storing State. The
storing entity may create unused apportionment by arranging for a willing third party to forbear
from its ordinary use of Colorado River water, However, it is more likely that the storing entity
would pump the groundwater previously stored to satisfY its needs and create unused
apportionment by reducing its Colorado River water order by an offsetting amount, After all of
the stored groundwater is removed, the aquifer would be at the same level as it would have been
in the absence of the off stream storage program. In Arizona, because of the requirement to leave
5% of the stored water in the ground, the water level in the aquifer would be slightly higher than
it would have been without the program.

The obligation to deliver 1.5 maf of Colorado River water to Mexico is set forth in the "Treaty
Between the United States and Mexico," signed February 3, 1944 and effective November 1945
(1944 Mexican Water Treaty) and Minute No, 242 of the Intemational Boundary and Water
Commission, Implementation of the Preferred A1temative will not impact the 1.5 mafMexican
treaty obligation. Mexico is also entitled to an additional 200,000 af of Colorado River water
during any year in which Colorado River water is available in excess of the quantity necessary to
supply the requirements in the United States and the guaranteed 1.5 maf annual quantity to
Mexico. The Preferred Alternative, which would allow surplus water to be stored off stream,
could result in a minor reduction in the quantity of surplus water available for delivery to Mexico
in the long term,

No Action Alternative

Under the No Action Alternative, without the proposed rule, the Secretary would continue to
deliver annual apportionments to the Lower Division States and Mexico, Nevada's declining
unused apportionment would be available for use in California and Arizona in a normal year,
Without the proposed rule it is possible that off stream storage credits could be developed
between California and Nevada for interstate redemption purposes, Reclamation would complete
the appropriate level ofNEP A analysis for such actions on a case-by-case basis.

C, Biological Environment

1, Wildlife and Threatened and Endanl1ered Species

Section 7(a)(2) of the Endangered Species Act (ESA) requires a consultation process to ensure
that Federal actions are not likely to jeopardize the continued existence of any listed species or
result in the destruction or adverse modification of critical habitat. Reclamation has prepared
numerous NEP A documents and entered into many section 7 consultations under the ESA with
the Fish and Wildlife Service (Service) for actions pertaining to the CAP in Arizona, the SNWS,
and the Lower Colorado River mainstem affecting the States of Arizona, California, and Nevada
that address potential effects to wildlife and threatened and endangered species (Appendix A),
These NEP A and ESA consultation documents are directly related to the analysis of potential
impacts on threatened and endangered species and their critical habitat from the proposed rule

LC Region DEAl I

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12/97