Home  >  The Inquiry  >  Why does Mexico owe the US water?
The Inquiry
Why does Mexico owe the US water?
The Inquiry
Sep 23, 2025

The major rivers of the Rio Grande and the Colorado run through both the United States and Mexico and they are the source of a water sharing agreement between the two countries that dates back to 1944.

Under the terms of this treaty, Mexico must send 430 million cubic metres of water per year from the Rio Grande to the US, to supply Texas and dozens of cities near the border. Whilst the US sends a much larger allocation of nearly 1.85 billion cubic metres of water a year, from the Colorado River to supply Mexico’s border cities like Mexicali and Tijuana.

But 80 years on, a deepening row over a shortage of water has put the treaty in jeopardy. Mexico is in arrears and has failed to keep up with its water deliveries to the US for much of this century and its unlikely to meet its obligation this year too. Farmers on both sides are struggling to water their crops, whilst the border cities are facing water shortages for both their populations and industries. And pressure on Mexico is mounting with President Trump earlier this year accusing Mexico of ‘stealing’ the water.

So this week on The Inquiry, we’re asking ‘Why does Mexico owe the US water?’

Contributors: Stephen Mumme, Emeritus Professor in Political Science, Colorado State University, USA Dr Rosario Sanchez, Senior Research Scientist, Texas Water Resources Institute, USA Susanne Schmeier, Professor in Water Co-operation, Law and Diplomacy, IHE Delft, The Netherlands. Naho Mirumachi, Professor in Environmental Politics, King’s College, London, UK

Presenter: Gary O’Donoghue Producer: Jill Collins Researcher: Maeve Schaeffer Technical Producer: Craig Boardman Production Management Assistant: Liam Morrey Editor: Tom Bigwood

{Photo: The Rio Grande River and surrounding land that divides the USA and Mexico. Credit: Daniel Slim/Getty Images)

More Episodes

Jun 2, 2026
Is Portugal’s drugs policy in need of reform?

In 2001, Portugal decriminalised the possession and use of all illicit drugs. It was a move designed to mitigate the country’s public health crisis, which at the time meant Portugal had one of the worst rates of overdose deaths in Europe, as well as the highest rate of HIV among drug users. Whilst drugs remained illegal, users did not receive a criminal record but were instead referred to rehabilitation and treatment programmes. It was an approach that proved so successful, that it has remained in place for a quarter of a century.

But just over 10 years after its introduction, Portugal’s drugs policy started to come under strain as the country’s economic crisis and subsequent austerity measures led to budget cuts for drug services. More recently the rising cost of living has diverted people’s attention from investment in this field. On top of this, the trafficking of cocaine and newer substances into the country along with changing demographics is putting decriminalisation under strain.

So, on The Inquiry this week, we’re asking ‘Is Portugal’s drugs policy in need of reform?’

Contributors: Joana Teixeira, President of the Board of Directors, Institute for Addictive Behaviours and Dependencies (ICAD), Lisbon, Portugal Luís Mendão, Director General, Grupo de Ativistas em Tratamentos (GAT), Lisbon, Portugal António Leitão da Silva, Chief of Police, Braga, Portugal Keith Humphreys, Esther Ting Memorial Professor of Psychiatry and Behavioral Sciences at Stanford University, California, USA

Presenter: David Baker Producer: Jill Collins Technical Producer: Toby James Editor: Tom Bigwood Production Management: Phoebe Lomas and Liam Morrey

(Photo: Discarded drug paraphernalia. Credit: Andy Buchanan/AFP via Getty Images)


23min 21sec

May 26, 2026
What’s the future for monetary unions?

At the beginning of this year Bulgaria, considered as one of the poorest countries in the European Union, became the latest to officially join the eurozone. Bulgaria’s legal tender since 1881 had been the lev, but since the mid-1990s it had been pegged to other European currencies, first to the German deutschmark and now to the euro. But it remains to be seen if the country’s economic policy can take advantage of the opportunities that joining the single currency can afford, in terms of trade and economic development.

Monetary unions are not a new concept, some like the Scandinavian monetary union date back to the 19th Century, involving Denmark, Sweden and Norway. It established a fixed exchange rate system based on the gold standard, whilst member countries still had their own currencies before it was gradually dissolved from the outbreak of World War One onwards.

Today, the biggest monetary union is the eurozone, used by around 358 million people across 21 European Union countries. It has one monetary authority for all the members and a standardised currency and coinage.

And now the Economic Community of West African States, known as ECOWAS is actively planning a monetary union with a common currency called the eco and pegged to the euro. The ambition is for greater economic sovereignty and regional economic integration.

But with the US dollar as the world’s dominant global reserve currency, even though it’s not part of a global monetary union, is there an argument for one currency across all borders and if so, what should it be?

So, on The Inquiry this week we’re asking, ‘What’s the future for monetary unions?’

Contributors: Assoc Prof Ralitsa Simeonova-Ganeva, Sofia University St Kliment Ohridski, Bulgaria Prof Barry Eichengreen, University of California, Berkeley, USA Prof Mohamed Ben Omar Ndiaye, Cheikh Anta Diop University, Senegal Dr Judy Shelton, Senior Fellow, The Independent Institute, California, USA

Presenter: Charmaine Cozier Producers: Daniel Rosney and Jill Collins Researcher: Evie Yabsley Editor: Tom Bigwood Technical producer: Toby James Production management: Phoebe Lomas and Liam Morrey

(Photo: Euro and US dollar banknotes. Credit: BBC/Corbis Royalty Free)


23min 15sec

May 19, 2026
Are the Himalayan glaciers at a tipping point?

The Himalayan glaciers are melting more rapidly as global temperatures rise, raising concerns about the future of ecosystems and communities across the Himalayan mountain range. Glaciers store more than two thirds of the world’s freshwater and help regulate global temperatures by reflecting the sun’s rays.

Across South Asia, melting ice is contributing to the formation of unstable glacial lakes and increasing the risks of floods, droughts and avalanches. The Himalayas are a vital source of water for millions of people, supporting agriculture, energy production and livelihoods from tourism.

Experts warn that continued glacier loss could have significant consequences for people living in the region and the mountainous ecosystem, but what can be done to respond to these changes?

Contributors: Pasang Yangjee Sherpa, assistant professor at the University of British Columbia, Canada Pam Pearson, director and founder of the International Cryosphere Climate Initiative, US Matthias Huss, glaciologist and senior scientist at the Swiss Federal Institute of Technology Zurich, Switzerland Alton Byers, faculty research scientist at the Institute of Arctic and Alpine Research at the University of Colorado, US

Presenter: Tanya Beckett Producer: Matt Toulson Researchers: Evie Yabsley and Amelia Cox Editor: Tom Bigwood Technical Producer: Mitch Goodall Production Management: Phoebe Lomas and Liam Morrey

(Photo: Trekkers walk to Everest Base Camp in Nepal. Credit: Kriangkrai Thitimakorn/Getty Images)


24min 30sec

Why does Mexico owe the US water?

--:--
--:--