WSP12647 ‎(2)‎

• File Number: 8282.400
• Description: Colorado River Operations and Accounting - Deliveries to Mexico
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1999
• Author: Environmental Defense Fund
• Title: A Delta Once More - Restoring Riparian and Wetland Habitat in the Colorado River Delta - Environmental Defense Fund - 06-01-99
• Water Supply Pro - Doc Type: Report/Study

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of Ecological Equilibrium and Environmental Protection
authorizes Biosphere Reserves, which are established
to protect areas of great biological diversity and unique
ecological characteristics (Valdes-Casillas et aI., 1998a).
To the extent that the ecological value of the Biosphere
Reserve in the delta is found in its wetlands, this law
might serve as a tool to secure or protect adequate flows,
which would be managed under the authority of CNA
for their conservation.

RELATED EFFORTS AND OPPORTUNITIES

Given the many competing demands for water in the
Colorado River basin, prospects for improving water
management to benefit the delta might be found in
conjunction with other, related efforts. Several resource
management issues that have been the focus of interna-
tional attention may offer strategic opportunities for
improving management of the delta.

Colorado River Entitlements and
California's 4.4 Plan

The amount of water that reaches the delta at present is
a function of water use and development upstream. The
existing regime of agricultural wastewater and periodic
flood releases will likely continue to sustain some areas
of the delta. Conservation measures taken upstream
(perhaps encouraged by market-based payments for
saved water) may result in increased flows. Deliberate
management of these flows could make a significant
difference in securing - and improving - the health of
delta ecosystems.

States in the upper basin (Wyoming, Colorado, Utah,
and New Mexico) do not at present use their full
allotment, and (with the exception of Colorado) are
unlikely to develop significant new uses for Colorado
River water in the foreseeable future. California, a lower

basin state, currently uses about 5.2 maf (6.4 x 109 m3) a
year, including surplus upper basin water and a dimin-
ishing quantity of unused lower basin entitlements.
Recently, California made a commitment to reduce its
use of Colorado River water to its original allotment of
4.4 maf (5.4 x 109 m3). Although its implementation
remains disputed, and California's" 4.4 plan" is not yet
operable or even fully defined, once implemented
(projected in 2010-2015) approximately 800,000 acre-feet
(9.9 x 108 m3) of water could remain in the basin in
normal years.54 Moreover, the period of mainstem
storage construction and reservoir filling is past. While
this condition of excess water in the system does not
guarantee delivery of water to Mexico, flows reaching
delta ecosystems are likely to be comparable to those of
the last decade as long as these conditions prevail.

Salton Sea

To solve pollution problems in the Salton Sea, resource
managers have proposed pumping Salton Sea water to
the Laguna Salada, a dry depression in the delta, or to
the Gulf of California. The Salton Sea and Laguna Salada
have become, in essence, evaporation basins that
concentrate pollutants and salts, and they are a hazard
to birds and other wildlife. [See Box 5.] Any consider-
ation of management options involving discharge of
Salton Sea water to the delta or Gulf of California will
require Mexican involvement, and thus may present an
opportunity for Mexico and the u.s. to consider
binational measures for enhancing delta ecosystems. 55
If the effluent and wastewater now dumped in these
closed basins were managed with care in the open delta,
they might actually bring some benefit to wetland
ecosystems. Flood flows could flush away any buildup
of pollutants or salinity.

54 Under the Law of the River, California has the right to 4.4 maf in normal years and up to 1 million acre-feet of surplus water in years when the Secretary
of the Interior determines that the water Is available. California water users have been diverting 5.2 maf or more from the river for many years. The Depart-
ment of the Interior and other Colorado River basin states support California's 4.4 Plan, announced in 1996. California water users, however, have yet to
agree on how to Implement these changes within the state (Metropolitan Water District of Southern California, 1999).
55 Any strategy to use delta wetlands to treat or remove pollutants or salinity in Salton Sea water (disposed there) must be carefully studied to avoid adverse
impacts on delta habitats and the species that inhabit them.

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