The Mexican Water Treaty of 1944 committed the U.S. to deliver
1.5 million acre-feet of water to Mexico on an annual basis, plus
an additional 200,000 acre-feet under surplus conditions. The
treaty is overseen by the International Boundary and Water
Commission.
Colorado River water is delivered to Mexico at Morelos Dam,
located 1.1 miles downstream from where the California-Baja
California land boundary intersects the river. The river’s
natural terminus is the Gulf of California in Mexico, but because
of the dams and diversion facilities throughout the Colorado
River Basin, natural flow rarely reaches the Gulf. Water diverted
at Morelos Dam is primarily used to irrigate Mexicali Valley
farmland, and also supplies the cities of Mexicali, Tecate and
Tijuana.
California public officials, scientists and coastal advocates
rang the alarm over the continued pollution of the Tijuana
River into the Pacific Ocean and nearby communities on the
Mexican border, describing the situation as one of the worst
public health and environmental disasters in the country and
around the world. … The Thursday [California Senate
Environmental Quality Committee] hearing invited a series of
panelists to explain the multifaceted issue to the public,
including oceanographers, air pollution experts and public
health experts, among others. … It is estimated that 40
million gallons of rancid sewage are dumped into the Pacific
Ocean every day, totaling billions of gallons per year,
according to the San Diego Coastkeeper.
President Donald Trump on Wednesday accused Mexico of posing a
“true threat” to residents of California and Texas, warning
that the country must “immediately” address cross-border water
and sewage problems. The president posted on Truth Social,
“Mexico must take care of its water and sewage problem,
IMMEDIATELY. It is a true Threat to the People of Texas,
California, and the United States of America!” The post
was accompanied by a video that says that “Mexico is sending
millions of gallons of untreated sewage water into the Tijuana
River.”
President Claudia Sheinbaum of Mexico struck a conciliatory
tone on Tuesday in response to President Trump’s threats of
additional tariffs over a long-running dispute between the two
nations over water. Mr. Trump said on Monday that he would
place an additional 5 percent tariff on Mexican imports if
Mexico didn’t release 200,000 acre-feet of water, or about 65
billion gallons, to the United States by the end of the year.
He said Mexico owed more than 260 billion gallons under a 1944
treaty mediating the distribution of water from the Rio
Grande, Colorado and Tijuana rivers. Ms. Sheinbaum
told reporters on Tuesday that … it was impossible to
immediately deliver the water Mr. Trump requested because of
physical constraints.
President Trump threatened on Monday to impose an additional 5
percent tariff on Mexican goods over a long-running water
dispute, reigniting diplomatic tensions that had flared earlier
this year over water shortages in the borderlands. In a social
media post, Mr. Trump accused Mexico of failing to provide more
than 800,000 acre-feet of water — or more than 260 billion
gallons — under a 1944 treaty mediating the distribution of
water from three rivers, the Rio Grande, the Colorado
and the Tijuana. The president said that Mexico needed
to “release 200,000 acre-feet of water before December 31st,
and the rest must come soon after.”
A new break in a Mexican sewer line has sent raw sewage to
South Bay communities, taking a toll on residents who live by
the Tijuana River and Imperial Beach in what locals call an
ongoing “sewage saga.” Officials with the U.S. International
Boundary and Water Commission say they were working on
improvements at the Hollister and Goats pump station when a
sewage line broke in Mexico, sending 120,000 gallons of sewage
through two layers of berms and vacuum trucks all the way to
Monument Road. The line broke because of recent rain.
… The U.S. and Mexico have agreed to what they call
permanent solutions, including a $600 million expansion of the
South Bay Treatment Plant.
Mexico’s national university and a U.S. NGO comprising water
management experts have agreed to jointly develop a digital
platform with information on the water resources that the two
neighboring countries share. The National Autonomous University
of Mexico (UNAM)’s Institute of Geography will work with the
Permanent Forum on Binational Waters (PFBW) to create and run
the platform that will include scientific data, maps and other
key information in Spanish and English about the shared water
sources in the border region, most prominently the Río Bravo
(Rio Grande on the U.S. side), the Colorado
River and the Tijuana River basin.
As the San Diego-Tijuana region continues to get pounded by a
series of storms, a trash boom strung across the Tijuana River
channel is working flawlessly. Oscar Romo, project manager for
Alter Terra, the group responsible for the boom, says by the
time all the rain passes, the device is expected to have
stopped about 50 tons of trash from Mexico. … “That’s a
result of culture of just dumping — not always purposely done,
but the city lacks good trash collection. People are also aware
that the rain takes away the trash so previous to a rain they
dump and we get all that,” Romo said.
U.S. Sens. Ted Cruz and John Cornyn, Republicans from Texas,
have filed a bill to hold Mexico accountable for failing to
provide water to south Texas in accordance with a 1944-era
treaty. The Ensuring Predictable and Reliable Water
Deliveries Act of 2025 would strengthen enforcement of the 1944
Treaty of Utilization of Waters, which governs water usage
between the U.S. and Mexico. … The bill would impose
restrictions and measures against Mexico if it does not meet
its average annualized obligation. It requires the secretary of
State to report to Congress on Mexico’s status of meeting its
treaty obligations. If the secretary finds that Mexico hasn’t
met its obligations, the bill directs the president to deny all
non-treaty requests from the Mexican government.
Last month, a trash boom strung across the Tijuana River
channel just inside U.S. territory stopped 40 tons of materials
during a one-hour rain event – as the trash gets removed and
sent to area landfills, another environmental issue has
surfaced. Dumps north of the border are having to take in the
additional trash coming in from Mexico compounding a critical
shortage of landfill space, according to Oscar Romo, director
of Alter Terra, a binational environmental group. All of it has
to go into a landfill in San Diego.
The County of San Diego has selected Olivewood Gardens and
Learning Center as the new operator of the Tijuana River Valley
Community Garden, ensuring continuity for hundreds of plot
owners at the region’s largest community garden. Olivewood
Gardens, a nonprofit founded in National City, will serve as
interim operator for up to one year following the Resource
Conservation District of Greater San Diego County’s decision to
terminate its lease in September due to health and safety
concerns related to the Tijuana River sewage crisis.
The Board of Supervisors discussed a resolution requesting
equitable Proposition 4 funding distribution for the New River
during the regular board meeting Tuesday, Nov. 4. Deputy CEO of
General Services for the County of Imperial, Gil Rebollar …
said that within the water chapter of Proposition 4, a
$10-billion climate bond that voters approved in Nov. 2024,
“there’s a specific line for California-Mexico rivers and
coastal waters.” … Rebollar said the resolution places
Imperial County on record as saying that the New River and
Salton Sea projects are eligible for a funding allocation and
emphasizes that Imperial County is seeking an equitable share
of the funding.
U.S. Sens. Ted Cruz and John Cornyn want to limit the U.S.’s
engagement with Mexico after the country failed to deliver
water to Texas under a 1944 international water treaty. The
Texas senators filed legislation Thursday that would limit the
U.S. from sending Mexico future deliveries of water and would
allow the U.S. president to stop engaging with Mexico in
certain business sectors that benefit from U.S. water. The
treaty requires the U.S. to deliver 1,500,000 acre-feet of
water from the Colorado River to Mexico every
year.
During a brief storm last month, a trash boom in the Tijuana
River managed to stop 20 tons of trash and debris from entering
California. Historically, during rain events in the San
Diego-Tijuana region, water flows from south of the border into
the U.S. carrying tons of plastic, tires and other debris. Last
year, as a way to stop the pollution, a 1,200-foot trash boom
was strung across the river bed by Alter Terra, a binational
environmental group. Sections of the boom float according
to the level of the river — its fence-like partitions stop the
trash from flowing farther into the Tijuana River Valley and
the Pacific Ocean.
A former Biden administration official who led water protection
efforts along the U.S.-Mexico border is now working at a major
engineering firm. Maria-Elena Giner, the former U.S.
commissioner of the International Boundary and Water
Commission, joined Black & Veatch last week as a portfolio
leader. She is on the firm’s water resources and community
planning team, working with federal agencies, state and local
governments, utilities and private companies, including tech
firms. Giner said her new role will focus on environmental and
infrastructure challenges affecting the water sector.
Learn the history and challenges facing the West’s most dramatic
and developed river.
The Layperson’s Guide to the Colorado River Basin introduces the
1,450-mile river that sustains 40 million people and millions of
acres of farmland spanning seven states and parts of northern
Mexico.
The 28-page primer explains how the river’s water is shared and
managed as the Southwest transitions to a hotter and drier
climate.
Martha Guzman recalls those awful
days working on water and other issues as a deputy legislative
secretary for then-Gov. Jerry Brown. California was mired in a
recession and the state’s finances were deep in the red. Parks
were cut, schools were cut, programs were cut to try to balance a
troubled state budget in what she remembers as “that terrible
time.”
She now finds herself in a strikingly different position: As
administrator of the U.S. Environmental Protection Agency’s
Region 9, she has a mandate to address water challenges across
California, Nevada, Arizona and Hawaii and $1 billion to help pay
for it. It is the kind of funding, she said, that is usually
spread out over a decade. Guzman called it the “absolutely
greatest opportunity.”
Water is flowing once again
to the Colorado River’s delta in Mexico, a vast region that
was once a natural splendor before the iconic Western river was
dammed and diverted at the turn of the last century, essentially
turning the delta into a desert.
In 2012, the idea emerged that water could be intentionally sent
down the river to inundate the delta floodplain and regenerate
native cottonwood and willow trees, even in an overallocated
river system. Ultimately, dedicated flows of river water were
brokered under cooperative
efforts by the U.S. and Mexican governments.
For the bulk of her career, Jayne
Harkins has devoted her energy to issues associated with the
management of the Colorado River, both with the U.S. Bureau of
Reclamation and with the Colorado River Commission of Nevada.
Now her career is taking a different direction. Harkins, 58, was
appointed by President Trump last August to take the helm of the
United States section of the U.S.-Mexico agency that oversees
myriad water matters between the two countries as they seek to
sustainably manage the supply and water quality of the Colorado
River, including its once-thriving Delta in Mexico, and other
rivers the two countries share. She is the first woman to be
named the U.S. Commissioner of the International Boundary and
Water Commission for either the United States or Mexico in the
commission’s 129-year history.
Nowhere is the domino effect in
Western water policy played out more than on the Colorado River,
and specifically when it involves the Lower Basin states of
California, Nevada and Arizona. We are seeing that play out now
as the three states strive to forge a Drought Contingency Plan.
Yet that plan can’t be finalized until Arizona finds a unifying
voice between its major water players, an effort you can read
more about in the latest in-depth article of Western Water.
Even then, there are some issues to resolve just within
California.
It’s high-stakes time in Arizona. The state that depends on the
Colorado River to help supply its cities and farms — and is
first in line to absorb a shortage — is seeking a unified plan
for water supply management to join its Lower Basin neighbors,
California and Nevada, in a coordinated plan to preserve water
levels in Lake Mead before
they run too low.
If the lake’s elevation falls below 1,075 feet above sea level,
the secretary of the Interior would declare a shortage and
Arizona’s deliveries of Colorado River water would be reduced by
320,000 acre-feet. Arizona says that’s enough to serve about 1
million households in one year.
The Colorado River Delta once spanned nearly 2 million acres and
stretched from the northern tip of the Gulf of California in
Mexico to Southern California’s Salton Sea. Today it’s one-tenth
that size, yet still an important estuary, wildlife habitat and
farming region even though Colorado River flows rarely reach the
sea.
This issue of Western Water examines the ongoing effort
between the United States and Mexico to develop a
new agreement to the 1944 Treaty that will continue the
binational cooperation on constructing Colorado River
infrastructure, storing water in Lake Mead and providing instream
flows for the Colorado River Delta.
As vital as the Colorado River is to the United States and
Mexico, so is the ongoing process by which the two countries
develop unique agreements to better manage the river and balance
future competing needs.
The prospect is challenging. The river is over allocated as urban
areas and farmers seek to stretch every drop of their respective
supplies. Since a historic treaty between the two countries was
signed in 1944, the United States and Mexico have periodically
added a series of arrangements to the treaty called minutes that
aim to strengthen the binational ties while addressing important
water supply, water quality and environmental concerns.
California’s little-known New River has been called one of North
America’s most polluted. A closer look reveals the New River is
full of ironic twists: its pollution has long defied cleanup, yet
even in its degraded condition, the river is important to the
border economies of Mexicali and the Imperial Valley and a
lifeline that helps sustain the fragile Salton Sea ecosystem.
Now, after decades of inertia on its pollution problems, the New
River has emerged as an important test of binational cooperation
on border water issues. These issues were profiled in the 2004
PBS documentary Two Sides of a River.
Redesigned in 2017, this beautiful map depicts the seven
Western states that share the Colorado River with Mexico. The
Colorado River supplies water to nearly 40 million people in
Arizona, California, Colorado, Nevada, New Mexico, Utah, Wyoming
and Mexico. Text on this beautiful, 24×36-inch map, which is
suitable for framing, explains the river’s apportionment, history
and the need to adapt its management for urban growth and
expected climate change impacts.
As part of the historic Colorado
River Delta, the Salton Sea regularly filled and dried for
thousands of years due to its elevation of 237 feet below
sea level.
The most recent version of the Salton Sea was formed in 1905 when
the Colorado River broke
through a series of dikes and flooded the seabed for two years,
creating California’s largest inland body of water. The
Salton Sea, which is saltier than the Pacific Ocean, includes 130
miles of shoreline and is larger than Lake Tahoe.
The Mexican Water Treaty of 1944 committed the U.S. to deliver
1.5 million acre-feet of water to Mexico on an annual basis, plus
an additional 200,000 acre-feet under surplus conditions. The
treaty is overseen by the International Boundary and Water
Commission.
Colorado River water is delivered to Mexico at Morelos Dam,
located 1.1 miles downstream from where the California-Baja
California land boundary intersects the river between the town of
Los Algodones in northwestern Mexico and Yuma County, Ariz.
The Colorado River Delta is located
at the natural terminus of the Colorado River at the Gulf of
California, just south of the U.S.-Mexico border. The desert
ecosystem was formed by silt flushed downstream from the Colorado
and fresh and brackish water mixing at the Gulf.
The Colorado River Delta once covered 9,650 square miles but has
shrunk to less than 1 percent of its original size due to
human-made water diversions.
This printed issue of Western Water examines how the various
stakeholders have begun working together to meet the planning
challenges for the Colorado River Basin, including agreements
with Mexico, increased use of conservation and water marketing,
and the goal of accomplishing binational environmental
restoration and water-sharing programs.
This printed issue of Western Water examines the
Colorado River Basin Water Supply and Demand Study and what its
finding might mean for the future of the lifeblood of the
Southwest.
This printed issue of Western Water explores some of the major
challenges facing Colorado River stakeholders: preparing for
climate change, forging U.S.-Mexico water supply solutions and
dealing with continued growth in the basins states. Much of the
content for this issue of Western Water came from the in-depth
panel discussions at the September 2009 Colorado River Symposium.
This printed copy of Western Water examines the Colorado River
Delta, its ecological significance and the lengths to which
international, state and local efforts are targeted and achieving
environmental restoration while recognizing the needs of the
entire river’s many users.
