The document discusses reviving the Rio Grande-Rio Bravo river, which runs through the US and Mexico and forms their border. It has lost over 80% of its natural flow due to dams, infrastructure, and overallocation of water. The World Wildlife Fund's vision is to restore ecosystem function and connectivity through "ecological pearls" - areas of healthy freshwater ecosystems. Restoring river flows is important but will require reducing water consumption, especially on irrigated farms which use over 80% of the water in the basin. Shifting crops and incentivizing some farm fallowing could save up to 28% of the water used. International cooperation and funding strategies will be needed to implement changes to save water

1. REVIVING THE RIO
Returning water to one of America’s most endangered and
climate stressed rivers: the Rio Grande-Rio Bravo
© Day's Edge / WWF-US
Water for Food Global Conference
University of Nebraska – May 2023
Enrique Prunes and Brian Richter, World Wildlife Fund

2. The Rio Grande-Bravo runs for 3,000
kms through the Southern Great Plains
and the heart of the Chihuahuan Desert.
It forms 2,000 kms of the shared
international boundary between the US
and Mexico.
Map Credit: Enrique Prunes / WWF-US

3. The Environment
The Chihuahuan Desert is one of
the three most species-rich deserts
in the world
 3,000 plant species
• 25% of all known cacti
 130 mammal species
• More than Yosemite NP
 500 bird species
• More than the Everglades
 50% of the fish species are
endemic
The People
In the US:
• 3 states
• 5 million people
• 23 tribal nations and
pueblos in New Mexico
• 2 tribal nations in Texas
In Mexico:
• 5 states
• 11 million people
• 4 indigenous groups in
Chihuahua
Rio Grande/Bravo Basin
Map Credit: Enrique Prunes / WWF-US

4. The RG-RB has been designated
as one of the
ten most endangered rivers in the
world
• The basin has a complex and fragmented water
governance and management
• The river has lost over 80% of its natural flow due
to dams, infrastructure and overallocation.
• Climate change and rapid population growth in
border cities are putting more pressure on the
already stressed river.
• The demand for water on farms is far greater than
what the river now provides
• The result is a river that now dries up in many
stretches and no longer flows into the Gulf of Mexico
in many years.
© Enrique Prunes / WWF-US

5. A heavily managed and overallocated basin
International Water Treaties and
U.S. interstate water compacts
• The Convention of 1906 – U.S. & Mexico
• The Rio Grande Compact of 1938 – CO, NM & TX
• The Water Treaty of 1944 - U.S. & Mexico
• The Pecos River Compact of 1948 – NM & TX
Water uses in the Rio
Grande/Bravo Basin
U.S. Mexico
Crop irrigation
-Cattle feed crops
-Cotton
-Pecans
86%
56%
4%
9%
84%
25%
25%
3%
Domestic supply 8% 13%
Commercial / industrial 4% 2%
Power generation <1% <1%
Mining <1%
Included in
industrial
Map Credit: Enrique Prunes / WWF-US

6. Average Annual Flow Depletion
• Ecological Impacts: At least 75 species imperiled by river
flow depletion
• Socio-Economic Impacts: In 2021 and 2022, farm water
deliveries within the Elephant Butte Irrigation District were
completely shut off in June, months before the end of the
growing season
Natural
Observed
Based on hydrologic simulation modeling by Dr. Ning Liu and Dr. Peter Caldwell,
US Forest Service Southern Research Station (NC)

7. So what are we going to do?

8. WWF’s Vision for
the Rio
Grande/Bravo
WWF envisions a healthy, flowing
Rio Grande/Bravo system with a
priority on restoring ecosystem
function and connectivity between
“socio-ecological pearls” through
binational collaboration and shared
governance between a wide range
of stakeholders that sustain thriving
communities, cultures, economies,
and biodiversity.
© Day's Edge / WWF-
US

9. WWF envisions preserving the river's essential
role in bringing life to the region by focusing on
restoring and revitalizing "Ecological Pearls" - or
areas of healthy freshwater ecosystems – and
connecting them with a more environmentally
friendly river flow pattern or “String”
A “String of Pearls”
Approach
Map Credit: Enrique Prunes / WWF-US

10. Basin Report Card collaborators
Dr. Casey Brown, Univ of Massachusetts – Amherst
Chinedum Eluwa, PhD Candidate, UMass
Alexandra Fries, University of Maryland
Dr. Katie May Laumann, UM
Paul Tashjian, Audubon

11. Building a Shared Vision
A 3-year effort involving 100
stakeholders from 63 organizations
across CO, NM, and TX
The Final Report Card was launched in November 2022,
with the participation of multiple stakeholders and invited
speakers representing the three states

12. Upper Rio
Grande
basin
health

13. Upper Rio Grande: CO Upper Rio Grande: NM
Middle Rio Grande Lower Rio Grande
Upper Rio Grande basin
health

14. Most of these conditions can be vastly improved by restoring river flows
Evaluation of Management Options
Colors indicate improvement (dark blue), some improvement (light blue), and decline (orange) in water indicators for each
management option. Gray shows no change.

15. The river that is The river we want
Current Future
Natural

16. How much water do we need to restore?

17. Environmental Flow Collaborators at UC Davis
Dr. Samuel Sandoval-Solis
Dr. Laura E. Garza-Díaz
Dr. Noelle Patterson
Ramon Saiz-Rodriguez, PhD Candidate
Gabriela Rendon-Herrera, M.S. Student

18. Characterizing a “resilient flow regime”
“Breaking point”

19. RGB at San Marcial (RG16_AT_SAN_MARCIAL)
Regulated (Modern Hydrology): 1975 - 2020
Natural streamflow: 1904 - 2015
Breaking Point: 1916
Resilient streamflow: 1900 - 1916
Overlaid Hydrograph with Functional Flow components
Environmental Flow Gap
Moderate
Year
Dry
year
Wet
year

20. Environmental flow gap for low-flow conditions in the
Middle Rio Grande during summer monsoon season
= 21 million cubic meters (17,025 acre feet)
= 23% of current consumption

21. Where will the water come from?

22. When it comes to saving water for the river,
we must reduce water consumed on irrigated farms
Water uses in the Rio
Grande/Bravo Basin
U.S. Mexico
Crop irrigation
-Cattle feed crops
-Cotton
-Pecans
86%
56%
4%
9%
84%
25%
25%
3%
Domestic supply 8% 13%
Commercial / industrial 4% 2%
Power generation <1% <1%
Mining <1% Included in industrial
Based on hydrologic simulation modeling by Dr. Ning Liu and Dr. Peter Caldwell,
US Forest Service Southern Research Station (NC)

23. Potential water savings in agriculture
Based on hydrologic simulation modeling by Dr. Ning Liu and Dr. Peter Caldwell,
US Forest Service Southern Research Station (NC)

24. Agricultural strategy collaborators
Dr. Landon Marson, Virginia Tech
Gambir Lamsal, PhD Candidate (VT)
Yufei Ao, PhD Candidate (VT)
Maria Amaya, Post-Doc (VT)
Dr. Kyle Davis, University of Delaware
Dongyang Wei, PhD Candidate (UD)

25. We need to understand what is being grown, and trends in the crop
mix over time

26. Crop Optimization Analysis
Objective
• Reduce water consumption using combination of crop shifting and
fallowing
Constraints
• Maintain or improve farmer revenues
• Substitute crops >10% of area within past 10 years
• Crop-specific area reductions range from 10-30%
• Total area of fallowing ranges from 0-40%

27. Potential water savings from crop shifting
ALFALFA
Blue water consumption: 5,593 m3/hectare
Net revenue: $966 per hectare
GREEN CHILE PEPPERS
Blue water consumption: 4,546 m3/hectare (-19%)
Net revenue: $19,281 per hectare (+20x)

28. Potential water savings from crop shifting & fallowing
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
orig 5% 10% 15% 20% 25% 30%
proportion
of
change
in
total
water
consumption
Allowable % change in crop-wise irrigated area (no fallowing)
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
orig 5% 10% 15% 20% 25% 30%
proportion
of
change
in
total
water
consumption
Allowable % change in crop-wise irrigated area (fallowing, no
payment)
fallowing <10% fallowing <20% fallowing <30% fallowing <40%

29. Farm fallowing
18-28% required

30. Shifting the crop mix
Scenario description ALFALFA BARLEY CORN OATS OTHER_HAY POTATO SPRING WHEAT CHILE PEPPER
current 78% 1% 3% 1% 13% 1% 1% 0%
sc1 zero fallowing cannot achieve 23% water saving.
sc2 no fallowing
payment; fallowing
area 18%; allow crop
area change 29%
49% 0% 0% 1% 19% 1% 1% 10%
sc2 no fallowing
payment; fallowing
area 26%; allow crop
area change 12%
66% 0% 0% 1% 5% 1% 1% 1%
sc3 fallowing payment;
fallowing area 18%;
allow crop area
change 28%
50% 0% 0% 1% 19% 1% 1% 10%
sc3 fallowing payment;
fallowing area 28%;
allow crop area
change 11%
67% 0% 0% 1% 5% 1% 1% 0%

31. Incentivizing changes on farms in the U.S.
• Federal Farm Bill: funding for crop shifting or fallowing
• Inflation Reduction Act: funding for drought-stricken farm districts
• Special legislation for Rio Grande: Rio Grande Water Security Act
• State funding: “Strategic Reserve” funding to ensure compliance with
Rio Grande Compact and Endangered Species Act
• Corporate Water Stewardship Programs
• Expanding markets for preferred crops, i.e., chile peppers

32. Thank you!