Deciding About the Colorado River Delta
About the Colorado River Delta
Rejuvenated
Wetlands Raise New Issues About Where Flood Flow Should
River Report, ,
Spring 1999, pp.1,4-9,11
By S. Joshua Newcom*
It starts as a trickle in the
mountains of Colorado - snow and ice melting to the demand of rising
temperatures. Tumbling thousands of feet, the alpine water melds into
a succession of creeks, springs and rivers, forming the waterway
known as the Colorado River.
Before the creation of state and
international boundaries, the unchecked Colorado wound its way
through the southwestern corner of North America and into what is now
known as Mexico. There, a combination of nutrient-rich water and silt
from the river created widespread wetlands - at times extending from
southern California where the Salton Sea is today to the northern tip
of the Gulf of California (gulf). Bordered by mountains and desert,
the historic delta comprised over 2.5 million acres of wetlands and
provided habitat for an estimated 400 species of plants and wildlife.
Along its shores, some 20,000 Cocopah Indians made a life from the
ecosystem by fishing, hunting and farming. The area became known as
the Delta del Rio Colorado - the Colorado River Delta.
Cienaga de Santa Clara
With completion of Hoover Dam in
1935, the United States began damming the Colorado River - on a much
larger scale than in the past - to meet the needs of burgeoning
cities and farms in the West. Nearly 30 years later, the last of the
great dams on the Colorado River was completed when the gates of Glen
Canyon Dam closed in 1963. Mexico, which at one time received the
full flow of the Colorado, agreed to an annual delivery of 1.5
million acre-feet (plus up to 200,000 acre-feet in surplus years) of
water under the Mexican Water Treaty of 1944, all of Mexico's river
apportionment is typically consumed by agriculture and municipal
industrial (M&I) uses in the Mexicali and San Luis valleys.
Thus, in a normal water year, the
last drop of the Colorado River evaporates in Mexican sands - about
1,450 miles from its birth and short of its natural termination in
Increased public interest in
environmental issues over the years has substantially boosted
attention to the delta from governments, non-governmental
organizations (NGOs) and environmental groups on both sides of the
border. According to U.S. fish & Wildlife Service (USFWS)
figures, over half of the wetlands in the United States have
disappeared since 1780. And according to the California resources
Agency, California, a major stopover for birds along the Pacific
Flyway, has only 10 percent of the wetlands that existed before
European settlement. The short-fall is this rich habitat has led some
to see Mexico's delta as a potential saving grace.
Nearly two decades of heavy rain and
snowfall, as well as the filling of Lake Powell, have boosted river
flows into Mexico. The Colorado River has reached the gulf five times
since 1983, most recently in 1998. Wetlands in the region have
benefited from the flood flows that have regenerated vegetation and
fish and wildlife populations. Sections of the delta and the northern
gulf support several endangered species like the totoaba, a fish
species once used commercially a the vaquita,
the world's smallest propoise and the desert
and endangered species of birds such as the southwestern
willow flycatcher and the Yuma clapper rail.
Questions now abound about
if and how to maintain and enhance these vital wetland
ecosystems, but a solution - like anything on the Colorado
River - is far from easy. In an act of protest, two
environmental groups within the United States have bowed out
of a steering committee for the Lower Colorado River
Multi-Species Conservation Program (LCRMSCP) claiming the
program falls short of addressing environmental needs in the
Mexican delta.
The LCRMSCP is an
environmental management plan for the Lower Colorado River
being implemented by the Bureau of Reclamation (Bureau) in
cooperation with the USFWS, the Lower Basin states, Tribes
and National park Service. (See Winter '98 River
The Colorado River flows to the Gulf of
California only in extremely wet years.
"Eighty percent of the top Lower
Colorado River habitat is in Mexico," said Tom Larousek, a
conservation associate with American Rivers (one of the letter's
signatories), an organization that listed the Colorado River Delta as
one of its top 10 endangered rivers in North America in 1998. "It is
a biological reservoir of sorts and if you enhance that habitat, you
enhance the recovery of species all the way up the Colorado River
into the U.S."
But state interests and the United
States government remain cautious about supplying more water to
Mexico. "We don't have any jurisdiction over how Colorado River water
is used once it crosses over the border into Mexico," said Robert
Johnson, regional director for the Bureau's Lower Colorado
This issue of River Report
examines the complexities surrounding the Colorado River Delta, its
ecological importance, the issues that impact it and what is being
done internationally to preserve and enhance its
existence.
Brief history of
Before humans began to build cities,
farm western soil and dam the Colorado, the delta was as untamed and
wild as the river that fed it. During a boating journey down the
Colorado River Delta for sunset Magazine in 1923, journalist
Lewis Freeman remarked: "At the time of which I write, indeed, it is
probably that no place in the world with the exception of the removed
regions of Africa harbored so great a variety of wildlife." Nearly 80
years later, the delta is a very different place, primarily due to
agricultural development and changes to both water quantity and water
quality resulting from controlled river runoff.
Prior to the completion of Glen
canyon Dam, between 4 and 6 millions acre-feet of Colorado River
water still inundated Mexico's wetlands in a normal water year.
Today, flows only reach the delta in very wet years. El Ni&o
created a succession of these wet years on the Colorado River system
from 1983-87 and once again, waters flooded the delta, scrubbing
floodplains, spreading tree and plant seeds and soaking lands that
had not been touched directly by the river's water in nearly two
Since the turn of the century, about
150,000 acres of wetlands in Mexico have been converted into
agricultural fields. Levees built by the Mexican government to
prevent flooding of farmlands follow the Colorado River from Morelos
Dam to the Gulf of California. The levees channel these flows and
have essentially created a revitalization of natural wetlands in
parts of the delta during abundant water years.
In 1993 the government of Mexico
declared 2.3 million acres of water and land in the Northern Gulf and
parts of the delta as the Reserva de la Biosfera del Alto Golfo de
California y Delta del Rio Colorado (Biosphere Reserve) - a region of
habitat managed and protected by the Mexican government. The reserve,
80 percent of which is aquatic, includes portions of the Rio Hardy
wetlands and the Cienega de Santa Clara (Cienega) in the deltas.
Activities in the core zone - about 400,000 acres - are limited to
research, small-scale shellfish harvesting and low-impact ecotourism.
Some in the United States view this protection of fish and wildlife
habitat as an indication of Mexico's commitment to ecosystem
preservation.
"Part of the Reserve's core zone
extends into about 72,000 acres of the delta," said Jos&
Campoy, director of the reserve, " and one of the major concerns of
the reserve is obtaining more fresh-water flows."
In the past year, the delta has been
the subject of two reports: "Importance of United States' Water Flows
to the Colorado River Delta and the Northern Gulf of California,
Mexico" (Glenn and Valdes-Casillas, October 1998) and "Wetland
Management & Restoration in the Colorado River Delta: The First
Steps," (North American Wetlands Conservation Council, November
1998). The reports are collaborative efforts between academic
institutions and NGOs in Mexico and the United States.
The studies make two strong
assertions about what could be done to improve the region:
The most valuable native riparian
habitat is in the 150,000-acre core of the delta, and
The delta can be sustained with
relatively marginal annual instream flows and periodic
In all, the reports conclude that the
Mexican delta contains nearly twice the riparian habitat and
marshland found along the adjoining stretch of river in the United
States from Davis to Morelos dams including cottonwood-willow forest,
flood plains and emergent wetlands.
Cienega De Santa Clara
wetland in the delta is an anomaly to the rest,
existing regardless of instream flows from the
Colorado River: The Cienega de Santa Clara
(Cienega).
1970s, the Cienega comprised less than 500 acres,
the result of natural artesian springs, tailwater
(agricultural runoff) from surrounding agricultural
lands in Riito and occasional high tides or storm
surges from the gulf. Today, the Cienega has
expanded to cover approximately 15,000 acres of
dense vegetation, due almost entirely to
agricultural return flows from the Wellton-Mohawk
Irrigation and Drainage District (WMIDD) across the
border in the United States. WMIDD diverts
approximately 400,000 acre-feet of Colorado River
water annually to irrigate crops. Already salty
Colorado River water, combined with the saline soil
of WMIDD farmlands, creates a saline groundwater
supply. As the underlying groundwater basin fills
with water from the irrigated fields, salts are
pushed to the surface. To keep the salts below the
root zone, pumps remove about 120,000 acre-feet of
brackish groundwater annually.
Initially,
the saline groundwater pumped from WMID farmlands
was blended with Colorado river water going to
Mexico. but Minute 242, negotiated in 1973 (an
addition to the '44 Treaty), curbed the amount of
salts allowed in credited water deliveries over the
border. To desalinate the Wellton-Mohawk drainage
water before its delivery to Mexico, the Bureau
constructed the world's largest reverse osmosis
water treatment facility in Yuma, Ariz. At a
construction cost of $250 million, the Yuma
Desalting Plant is designed to treat up to 96,000
acre-feet of water annually.
construction of the treatment plant, a $45 million
drainage canal was constructed in 1977 to dispose
of the brackish WMIDD groundwater until it could be
treated by the plant. The bypass drain transports
the salty drainage water 50-miles south into the
Cienega. (This water does not meet international
salinity requirements and is not counted towards
Mexico's Colorado River apportionment.)
the Yuma Desalting Plant has never been fully
online. It operated at one-third capacity of nearly
a year, but a flood on the Gila river in 1993
washed out a section of the drainage canal, halting
operation. In the meantime, the Yuma Desalting
Plant is being kept in "ready reserve" at a cost of
$6 million a year. the possibility of operating the
plant looms closer as water use on the Colorado
continues to grow.
is recognition that operation of the desalting
plant will decrease the quantity and increase the
salinity of the water traveling to the Cienega,"
said William Rinne, are manager for the Bureau's
Lower Colorado Region. "I would expect the Cienega
to become more limited in terms of what it could
sustain," he said. Rinne said that bypass drain
would still be used to discharge the salty
byproduct of the desalting plant to the
Additionally, the
reports conclude that riparian habitat mitigation
can be sustained with a relatively nominal amount
of water annually - perhaps less than 1 percent of
normal river flow, augmented by treated wastewater
streams and occasional flood releases.
"Because the
primary water needs in the delta are intermittent,
it doesn't require huge amounts of the river's
annual flow,," said Edward Glenn, a professor in
the Department of Soil, water and Environment at
the University of Arizona and one of the lead
scientists in the studies. "Around a half-million
acre-feet of water every three to four years would
probably take care of riparian habitat for the
Using satellite
photos, aerial videography and photos, ground
surveys and extensive on-site work including
vegetative analysis and mapping, water quality
analysis and community outreach, the group of
researchers compared high-flow years in the delta
with low flow years.
The studies
estimate that the delta's core can be flooded with
about 256,000 acre-feet of water, a process
important to germination for the delta's
vegetation, according to Glenn. This number was
achieved by examining the records of flows through
Morelos Dam and a comparison of delta vegetation
during those corresponding flows. The studies
showed trees were able to continue growing during
three or four successive years of receiving no
water, thus concluding that overbank flooding of
the delta core is needed every four years to
sustain existing vegetation and that more frequent
floods could expand the scope of the riparian zone.
Approximately 32,000 acre-feet of inflows annually
to the delta are sufficient to maintain the
cottonwood-willow gallery forest, a habitat capable
of supporting a wide variety of birds and
Although the Bureau
is interested in information about the ecology of
the delta, officials remain cautious about the flow
requirement findings in the reports.
"At present, it is
difficult to evaluate the accuracy of the estimates
because there is not a good understanding of how
the data was generated and the assumptions made
about conditions which existed within the river
corridor preceding these flow events," said William
Rinne, area manager for the Bureau's Lower Colorado
To help solidify
the answers, a joint effort is underway between
USFWS and universities in the U.S. and Mexico to
conduct field studies of wildlife and vegetative
counts in the delta.
"The delta is one
of the most important migratory routes in all of
North America," said Charlie Sanchez, associate
regional director for international affairs with
the USFWS. "We have to leave a legacy in the
protection of these resources."
Sanchez said he is
working with affiliates in Mexico and the United
States to conduct population assessments of species
like the Yuma clapper rail and the desert
pupfish,to assess the riparian values of delta
wetlands areas and to map those areas.
So far, Sanchez said Interior has spent
around $909,000 to initiate the studies.
Glenn said some of the information
will be incorporated into a third study planned for publication later
this year that makes specific recommendations for managing habitats
in the delta region.
There are those who
would like the United States to be required to
release Colorado River flows for the environment,
including the delta. But this idea has sparked
considerable debate among policy makers because of
legal constraints and the lack of additional water.
"Water and power
agencies in the U.S. want all Colorado River water
for use in the U.S. and refuse to allocated any for
conservation purposes," said David Hogan, river
program coordinator for the Southwest Center for
Biological Diversity, an environmental group based
in Tucson, Ariz.
The Southwest
Center, along with Defenders of Wildlife, pulled
out of a process to develop a LCRMSCP - the
management plan for fish, wildlife and habitat on
the U.S. portion of the Lower Colorado River -
because the plan would not address the Mexican
The Yuma clapper rail is one of the delta's endangered
In March 1999, a letter was addressed
to Interior Secretary Bruce Babbitt from the Southwest Center and
eight other organizations expressed their dismay over what they
consider to be shortcomings of the program.
"Conservation planning that stops at
geopolitical borders without regard for ecosystem boundaries and
sound conservation biology principles is domed to fail," they wrote.
The letter also condemns a resolution passed by the Colorado River
Board of California stating its desire to limit the LCRMSCP to the
United States.
"We must also come
up with a solution about how to approach Salton Sea
restoration in a way that isn't detrimental to the
Delta, " said Jason Morrison, a senior associate
with the Pacific Institute.
The February 1999
Pacific Institute study, entitled "Haven or Hazard:
The Ecology and Future of the Salton Sea"
recommends that restoration plans for the 35-mile
long Salton Sea be coordinated with restoration
efforts in the delta. Part of the same historical
basin, the report denounces proposed restoration
alternative that would divert Colorado River flood
water away from the delta to the Salton Sea or pump
in potentially harmful brine water from the Salton
Sea somewhere near the delta.
But not everyone
agrees with the Institute's
recommendations.
"In a perfect
world, barring political, practical and economic
considerations, the ecology of all these places
would get comprehensively studied and managed,"
said Tom Kirk, executive director of the Salton Sea
Authority. "We do not live in a perfect
Kirk went on to say
that due to time constraints under the Salton Sea
Reclamation Act of 1998, scientists working on the
sea must make recommendation to Congress by January
"It was the board's
opinion that with the limited time and money
available to us, what we need to do now is focus on
developing the LCRMSCP within the U.S.," said
Gerald Zimmerman, executive director of the
Colorado River Board of California. Currently in
development, the 50-year LCRMSCP is expected to be
ready for implementation by 20001. "There is the
adaptive management component of the LCRMSCP that
encourages the exchange of information between U.S.
and Mexican officials and could allow for expansion
into the delta once the LCRMSCP is implemented," he
Under a separate
effort, a coalition of U.S. government departments
and agencies, and their Mexican counterparts, have
entered into discussions with the Mexican
government via the International Boundary and Water
Commission (IBWC). The IBWC is the arm of the U.S.
government that handles issues associated with
water deliveries to Mexico such as the availability
of water and when such water can be
delivered.
"Discussion of
restoring the delta was added to our agenda about a
year ago," said John Bernal, commissioner for the
United States Section of the IBWS. Bernal said the
IBWC has facilitated one major meeting and several
technical -level working sessions with various U.S.
and Mexico federal and state agencies to determine
what still needs to be gathered. "We are addressing
the challenge of assuring conditions in the delta
do not deteriorate any further and that preferably
valuable resources are sustained," he
In May 1997 - the same year work began in earnest on developing
the LCRMSCP - Babbitt and Julia Carabias Lillo, Mexico’s
secretary of Environment, Natural Resources and Fisheries, signed a
Letter of Intent in which their "two agencies plan to expand existing
cooperative activities in the conservation of contiguous natural
protected areas in the border zone, and to consider new opportunities
for cooperation in the protection of natural protected areas in the
United States-Mexico border." The letter was the latest in a series
of agreements between the countries intended to augment binational
protection and enhancement of the border environment through an
exchange of scientific information, community outreach programs and
joint studies.
But for the Southwest Center’s
Hogan, the time for increased water deliveries to Mexico is now. He
said that center could sue to try and get committed river flows for
the delta by proving the United States is responsible for endangered
species protection in Mexico. "It’s a simple issue of
encouraging the U.S. to take responsibility for the effect of
exploiting the river," he said.
Supplying the
If it were determined that more water
should be given for the delta, how to increase those allocations to
Mexico without reopening the Law of the River is considered by many
to be a major undertaking and one that could involve massive
litigation. The 1922 Colorado river Compact only allocated water to
seven U.S. states and, despite subsequent state, federal and
international agreements, treaties, court decisions and legislation,
the environment is only recognized as a limited "user" of the
Colorado River. (Water was allocated under the 1968 Colorado River
Basin Project Act for a number of wildlife refuges within the
Stakeholders
Over 200,000 people live in the delta area (not
including Mexicali), members of what remains of the
Cocopah Indian tribe near El Mayor, a tributary to
the Hardy River. Part of the equation for restoring
the delta is to involve these communities in
discussions about the delta. Goals of an outreach
program organized and funded by the North American
Wetlands conservation Council, a coalition
supported by federal, academic and nongovernmental
entities include:
Identifyin
Explaining restoration possibilities and
determining if the stakeholders are interested
Bringing stakeholders, local government
leaders, research centers, academics, NGOs and
policy makers to the table and facilitate
discussions about what everyone's needs from the
Conducting workshops and conferences to
discuss restoration plans and
implementation.
"Part of the niche we are trying to fill in the
absence of community leaders in modifying and
changing the use of water in the delta," said Steve
Cornelius, director of borderlands program for
Tucson-based Sonoran institute, one of the
participants in the program. "Managing the delta
has to be beneficial to the communities using the
Cornelius said he expects the process, which has
been spearheaded in the Rio Hardy Wetland area, to
take up to seven years to complete. "We need to
understand what the various stakeholder positions
are and they need good, solid, scientific
information in order to design a position," he
Carlos Vald&s-Cassillas, director of the
Center for Conservation and Use of Natural
Resources at the Monterey Institute in Guyamas
"The best possibility for accomplishing a
management plan for the delta is to look at a more
effective use of water including reuse of
agricultural run-off and additional instream flows
during flood years," he said. "We must look to
different institutions and water users to partake
in the responsibility."
Other groups taking part in the process include
Pronatura Sonora, the University of Arizona,
California State University, Dominguez Hills and
the Environmental Defense Fund.
of programs and treaties have been
implemented over the past 50 years to
address border issues, but none has dealt
specifically with the delta region. The
Border XXI Program and North American Free
Trade Agreement are two examples of major
binational agreements that include
environmental provisions, but neither has
the authority to allocate more Colorado
River water for the delta.
parties in the United States, a major
concern of allocating greater flows to
Mexico is a lack of certainty over how
water intended for environment would be
used. The Mexicali Valley relies on the
Colorado and Gila rivers for nearly 100
percent of its water supply. Preliminary
calculations by the Pacific Institute in
its 1996 report "The Sustainable Use of
Water in the Colorado River Basin"
indicate that the Mexicali Valley is
suffering from a groundwater overdraft of
roughly 96000 acre-feet annually. The
overdraft could become even greater with
the added lining of the All American Canal
north of the border - a source of
groundwater recharge for Mexico. Mexico's
desire for more water has given rise to
fears that increased flows to Mexico would
be used to recharge goundwater overdraft
or to irrigate fields in Mexico instead of
as instream flows for the
environment.
proposed method for earmarking additional
flows to Mexico for instream purposes is
amending the existing Law of the River.
Some have used Minute 242, the addition to
the 1944 Treaty with Mexico that improved
the quality of water deliveries to Mexico,
as an example of a potential way to
permanently mitigate water for fish,
wildlife and habitat in the delta.
Similarly, some purport that a like
measure could modify the Colorado River
Basin Salinity Control Act of 1974 to
ensure continued deliveries of equal or
better quality water to the
The Colorado
River Delta in a Glance
The Riparian
Corridor (1)
Bordered by farmland levees.
Stretches about 70 miles from Morelos Dam to the junction with the
Hardy River. Contains large stands of cottonwood and willow trees
measuring 13-feet to 50-feet tall, from high water in the 1980s and
saplings from recent floods in 1993 and 1979.
The Rio Hardy
Wetland (2)
Maze of sloughs and old river
channels and confluence of the Hardy and Colorado rivers. High
salinity levels in area due to high tides from the gulf 35 miles
away, geothermal wells and agricultural drainage. Some cottonwood and
willow trees in northerly portion giving way to more salt-tolerant
vegetation including, salt cedar, mesquite, areas of Palmer’s
saltgrass and cattails. Once a natural earthen dam located 21 miles
northwest of gulf created a natural 45,000 acre floodplain that grew
to 160,000 acres with ‘80s upstream releases. Wetlands shrunk to
3,000 acres after dam breached by floods. Ducks Unlimited studied
rebuilding the natural dam, but determined frequency of flows too few
and of poor quality.
Only during very wet years does water
reach this salt flat. In majority of years, area looks like a desert
Cienega de Santa
Largest and one of the most
biologically rich delta wetland areas. Supported by brackish
agricultural flows in the U.S. and Mexico and natural artesian
springs. Supports large populations of endangered desert pupfish and
Yuma clapper rails.
El Doctor Wetlands
1,700 acre wetland fed primarily by
natural springs. Area biologically rich and believed to contain over
22 different types of plant species and endangered desert
El Indio Wetlands
Covers over 4,000 acres fed by return
flows from surrounding San Luis farmlands. Agricultural flow once
followed a drainage channel back to the river wetlands but around
1993, the drain was damaged and flows spilled outside the flood
plain. Typical regional coastal wetlands vegetation, primarily salt
cedar, mesquite, Palmer’s grass and cattails.
Intertidal
Wetlands (7)
Mudflat much of the time, though an
estuary during we years. 13 mile-long section provides - at times -
spawning habitat for numerous species, including corvina, totoaba and
shrimp. Easily disrupted by a lack of fresh water, creating water too
saline to support the propagation of many species.