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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ENViRON1V!EN1AL DEFENSE FUND

TICAL LANDSCAPE

The old ideas continue to rule most of western water. But reform will come. There are too many physical,
economic, and social imperatives for vested interests to hold the existing structure in place indefinitely.

-Charles F. Wilkinson, The Eagle Bird: Mapping a New West, 1992

VALUES OF THE COLORADO RIVER DELTA

A century of development in the Colorado River basin
has degraded the delta, yet, as documented throughout
this report, its vestigial wetland and riparian ecosystems
remain ecologically, economically, and socially impor-
tant. Delta ecosystems harbor migratory shorebirds
traveling along the Pacific Flyway; serve as a breeding
ground for marine species in the Gulf of California;
provide habitat for a number of endangered species; im-
prove the quality of water that flows in from various
sources and out to the Gulf; deliver a steady flow of
fresh water to near-shore marine (brackish) environ-
ments in the Gulf, improving breeding and nursery
grounds for the endangered vaquita; and produce
vegetation important to indigenous peoples (Glenn et
aI., 1992 and 1999). In addition to these environmental
services, the delta historically has been a source of
income for surrounding communities, supporting lucra-
tive fisheries. Although local communities no longer
rely as extensively on fishing for income due to the
recent decline of shrimp, totoaba, and other traditional
harvests, some have generated income by working as
guides for visitors who wish to hunt and fish. Interest
in ecotourism as a sustainable use of delta wetlands is
growing (Valdes-Casillas et aI., 1998a). Finally, the
delta's social value cannot be overlooked. The social
fabric of many small communities, ejidos, and Cucapa
settlements in the delta region would disintegrate with
the collapse of delta ecosystems (Williams, 1983; Valdes-
Casillas et aI., 1998a). The small delta communities will
literally "dry up" if the wetlands disappear.

PRESERVATION STRATEGIES

As demonstrated by the analysis of flood flows and
vegetation, preserving the delta's wetland habitats will
require relatively modest, yet secure, supplies of good-
quality water each year, as well as periodic, but assured,
flushing flows. Partial recovery after recent floods dem-

onstrates that delta ecosystems can be sustained even
with limited water resources. Although more water
would without doubt further improve the habitat, what
is most critically required now is not more water, but
water delivered on a reliable schedule. This would
require a commitment from the U.S. (and the myriad
stakeholders in the U.S.) to release flood waters at
critical intervals to support the newly established habi-
tats of the delta. Together with the monitoring and
management of water quality, these releases could bring
some delta ecosystems back to health.

One short-term strategy is to provide regular flood
releases every few years to saturate riparian and wet-
land areas. This could be done with little or no impact
on current water allocations. Effectively, this will require
the managers of the Biosphere Reserve, working with
research institutions, to determine the best flow regime
for existing water to benefit delta wetlands. Once
established, this plan for optimum flows could be used
by the Mexican federal government to develop a strat-
egy to achieve them based on recent hydrologic data.
Finally, implementation of any such plan would require
coordination among the many agencies and authorities
with a stake in management of these resources. For the
long term, delta ecosystems may require the allocation
of additional water supplies secured through negotia-
tions and cooperative management agreements among
governments and water users in the United States and
Mexico.

The apparent simplicity of maintaining present flows is
false: securing these flows will not be easy. Allocation
of water in the Colorado River has a long and conten-
tious history. A long-term solution will involve
binational institutions, nine states in two nations,
dozens of tribes, and innumerable stakeholders, and
may necessitate changes to the treaty. Ultimately, the
best preservation strategy will treat the delta and the