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)