A water dispute between the United States and Mexico is worsening political tensions and human suffering along the border, a region already hit hard by climate change in recent years. Amistad Reservoir that sits on the U.S.-Mexico border supplies water to Texas and northern Mexico. At the dam that marks the international frontier, political tensions over the two countries' water sharing treaty have left levels on the south side critically low. Within days of Donald Trump's threat to impose tariffs over Mexico's water deliveries to Texas, Mexico's federal government drained the Amistad Reservoir to its lowest-ever levels, worsening the water problems in this region -- already struggling with prolonged drought. On the Mexican side in Acuna, Paula Ibarra watches the water levels drop daily. "They are still emptying the reservoir, the floodgates are open 24 hours a day. Its levels are at less than 10 percent, so we're worried," said Paula Ibarra, Ciudad Acuna resident. "The U.S. President has forced Mexico into delivering its water, and we're afraid of running out," said another resident named Alejandro Bravo. As Mexico drained its water resources, the region erupted in protests observed by water scientist Rosario Sanchez. "People were protesting, the State of Coahuila protested, the cities protested, the mayors protested like; hey, what am I supposed to do in summer without water?" said Rosario Sanchez, senior research scientist at Texas Water Resources Institute. The treaty, signed in 1944, stipulates Mexico deliver over two billion cubic meters of water to Texas every five years, but former Coahuila state federal congressman Lenin Perez says those continued volumes will leave his region high and dry. "Trump needs to realize that we can't deliver these quotas of water when those water volumes simply don't exist. Climate change is a reality. It doesn't rain, we don't have enough water, and we are approaching a crisis," said Lenin Perez, former Mayor of Ciudad Acuna. "The Rio Grande has lost 80 percent of its natural flow over the last 100 years. It's not like Mexico is going to invent water out of nothing, and it's not like Mexico doesn't want to comply. It wants to comply. Who has the priority? Where does the human right to water sit in this context, at the transboundary scale?" sadi Sanchez. SHOTLIST: Del Rio, Texas, USA - Recent 1. Various of Amistad Reservoir, dam; 2. Various of Paula Ibarra, Ciudad Acuna resident, checking water levels; 3. SOUNDBITE (Spanish, dubbed in English) Paula Ibarra, Ciudad Acuna resident (starting with shot 1/ending with shot 4): "They are still emptying the reservoir, the floodgates are open 24 hours a day. Its levels are at less than 10 percent, so we're worried."; 4. Various of river, national flag of Mexico, traffic on bridge; 5. SOUNDBITE (Spanish, dubbed in English) Alejandro Bravo, Ciudad Acuna resident (starting with shot 4): "The U.S. President has forced Mexico into delivering its water, and we're afraid of running out."; 6. Aerial shot of city view; 7. Rosario Sanchez, senior research scientist, Texas Water Resources Institute, speaking; 8. SOUNDBITE (English) Rosario Sanchez, senior research scientist, Texas Water Resources Institute: "People were protesting, the State of Coahuila protested, the cities protested, the mayors protested like; hey, what am I supposed to do in summer without water?"; 9. River; 10. SOUNDBITE (Spanish, dubbed in English) Lenin Perez, former Mayor of Ciudad Acuna (starting with shot 9/partially overlaid with shot 11): "Trump needs to realize that we can't deliver these quotas of water when those water volumes simply don't exist. Climate change is a reality. It doesn't rain, we don't have enough water, and we are approaching a crisis."; [SHOT OVERLAYING SOUNDBITE] 11. River; [SHOT OVERLAYING SOUNDBITE] 12. Aerial shots of river, residential houses; 13. SOUNDBITE (English) Rosario Sanchez, senior research scientist, Texas Water Resources Institute (starting with shot 12/ending with shot 14): "The Rio Grande has lost 80 percent of its natural flow over the last 100 years. It's not like Mexico is going to invent water out of nothing, and it's not like Mexico doesn't want to comply. It wants to comply. Who has the priority? Where does the human right to water sit in this context, at the transboundary scale?"; 14. Aerial shot of river, residential houses. [Restrictions: No access Chinese mainland]