Water shortages are increasing along the South Texas border because supplies cannot keep up with growth and Mexico has not paid the United States for the water it owes.

About 250 lawmakers met in the border town of Pharr on Tuesday for the Deep South Texas State of Water Symposium.

The bipartisan event was organized by Democratic Texas State Representative Terry Canales and Democratic Senator Juan “Chuy” Hinojosa, along with the Texas Water Foundation. Republican Representative Monica De La Cruz, who represents South Texas, participated in the discussion.

Sarah Schlessinger, executive director of the Texas Water Foundation, said water supplies cannot keep pace with Texas’ population growth: The state expects a 70 percent growth spurt over the next 50 years.

There are several other reasons for the water shortage, including the fact that South Texas has experienced prolonged periods of drought.

Dr. Robert Mace, who specializes in hydrogeology at the University of Texas at Austin, said Newsweek: “The Rio Grande below Presidio, Texas, and Ojinaga, Mexico, supports agriculture, industry, and over 2.6 million people who live on both sides of the river. For much of the river’s history, since the international agreement in 1944, the primary form of management has been to ‘hope for a hurricane’ to fill the reservoirs.

“Increased river use, drought and global warming are causing reservoirs to reach historic lows, threatening the entire valley. Solutions often come from discussion and understanding. This symposium will hopefully start that process toward a more water-resilient future. It is becoming increasingly clear that simply praying for a hurricane is not enough.”

Another problem is the state’s dependence on surface water, particularly the Rio Grande River, on which the Rio Grande Valley is “90 percent dependent,” according to Maria-Elena Giner, U.S. commissioner of the International Boundary and Water Commission, told local newspaper ConchoValley.

A few weeks ago, Giner published a report saying that the United States had contributed less to the river in recent years.

“It was a very scary thing for me as the head of this agency, and it’s very uncomfortable for people, but I felt like it was our duty as an agency,” she said.

The other major problem is that Mexico owes water to the Rio Grande under the 1944 water treaty between Mexico and the United States, officially known as the Treaty for the Use of the Waters of the Colorado and Tijuana Rivers and the Rio Grande.

Mexico is supposed to deliver 350,000 acre-feet of water annually over five years. But as of Aug. 10, Mexico has paid the U.S. only 400,100 acre-feet of water in the current five-year cycle that ends in October 2025, according to the International Boundary and Water Commission.

Mexico had previously argued that it was having difficulty meeting its water needs due to the drought. Newsweek has asked the Mexican Foreign Ministry for further comment.

John Nielsen-Gammon, professor of atmospheric sciences at Texas A&M University, said Newsweek: “This is the biggest water problem for Texas. Mexico is contractually obligated to deliver a certain amount of water every five years, but there is no obligation to distribute it evenly. During recent droughts in northern Mexico, preserving local agriculture was considered the top priority. It was politically impossible to do otherwise, and now they have no choice but to hope for a nice, wet hurricane.”

Mace added, “Water is a bipartisan and binational issue on the Rio Grande in Texas, so I commend the organizers for holding a symposium to increase understanding of the complicated and truly serious problems facing the river.”

Texas Water Foundation CEO Schlessinger said Newsweek: “The demands on the Rio Grande/Río Bravo have become greater than the river can reliably handle. If the Rio Grande Valley wants to have a secure water supply in the future, communities must work together to diversify their water supplies and increase efficiency.

“The symposium brought together leading representatives from federal, state, county and municipal governments from across the region to exchange ideas and discuss where there are common challenges and opportunities.”