MCALLEN, Texas (AP) – On a scorching afternoon in South Texas, Sonia Lambert watched an open-cast canal that carries mud-green water from the Rio Grande to nearby towns and farmland, losing out much of it because of evaporation and seepage along the way.
“It will be someone else’s problem,” Lambert said, referring to his upcoming retirement as head of an irrigation district near the US-Mexico border.
In the Rio Grande Valley, a canal system designed over a century ago for agriculture still provides water to the region’s lush farmlands and rapidly growing towns and villages. Today, canals lose up to 40% of the water they carry, waste that experts say could contribute to severe water shortages in the decades to come as the population increases and that climate change intensifies droughts.
“As this region continues to get drier due to climate change, water supplies will be drastically reduced,” said Guy Fipps, professor of irrigation engineering at Texas A&M University who studies the system. water since 1998.
State water officials predict that over the next 50 years, the demand for water in towns and villages across the region will double. For decades, McAllen has grown at a breakneck pace, with newcomers drawn to a large free trade area and jobs in healthcare, education, and retail. Between 1990 and 2020, McAllen and the neighboring towns of Edinburgh and Mission grew six-fold to nearly 871,000 residents, according to the US Census Bureau. Likewise, the Mexican towns of Reynosa and Matamoros across the border flourished after the establishment of US-owned assembly plants in the mid-1990s.
To further complicate matters, a 1944 treaty between the United States and Mexico defines how countries share the water in the Rio Grande. Mexico is supposed to deliver 350,000 acre-feet of water each year to the United States, enough to supply up to 700,000 households. But it has periodically defaulted on those obligations, delaying deliveries due to drought, water shortages and a thirsty agricultural industry in northern Mexico.
Late deliveries are a source of frustration, but water managers and farmers in the United States are quick to recognize a major challenge within them too: the leaky canal system that has long been considered by local authorities and states as too costly to review.
The region’s more than 2,000 miles (3,219 kilometers) of pipelines and canals – about 100 feet (30 meters) wide – are intended for large and infrequent deliveries to farmland. Common solutions to modernize waterways and make them more efficient – attempted by many districts to some extent – include lining earthen channels with concrete and closer monitoring of water use by farms. with counters. Another option comes at a higher price: replacing canals with underground pipes, which lose much less water and are better suited to serve cities.
Converting a mile of open-pit canal to underground pipes costs between $ 250,000 and $ 1 million, said Lambert, director of the Irrigation District for Cameron County, which remains predominantly rural. Her district has only been able to dig about a fifth of its 250 miles (402 kilometers) of underground canals over the past two decades, she said.
“This is just an amount that could not be supported by the farming community,” Lambert said.
Since the early 1900s, a network of about two dozen independent irrigation districts have served farmers, towns and villages in the region. But as McAllen has swallowed up much of the farmland surrounding it, some officials wanted more control over a river basin district they say charges the city too much for water deliveries.
Still, the higher rates charged to city water utilities are often how irrigation districts pay for canal repairs, Fipps said. This means that river basin districts serving large cities have generally made more progress in updating canals.
Yet water utilities and farms in the Rio Grande Valley are linked by the same aging system.
Since cities and farms get their water from the same canals, hydrologists and water officials say the declining flows of the Rio Grande and low reservoir levels could potentially cause problems for everyone in the event. prolonged drought. When there is little water in a channel, a greater percentage is lost through evaporation or infiltration. And everyone’s water share is threatened.
Already, experts say demand for water from the river exceeds supply.
Small towns, which receive relatively low water deliveries, could be particularly affected during a severe drought, and their irrigation districts are less likely to have the money to repair or replace canals.
“It is an unusual situation for agricultural canals to be used to help provide municipal water,” Fipps said.
Over time, experts say farms in the region will face increasingly severe water shortages and be forced to make more difficult choices, a scenario that is already playing out in parts of the West. American. Over the years, some irrigation districts have received state or federal funding via grants administered by the Bureau of Reclamation for repairs, but water managers, farmers and hydrologists say that insufficient money for full repairs. The Texas Water Development Board predicts that by 2070, the water used to irrigate farms in the Rio Grande Valley will decline by 36%, largely because more farmland will be replaced by urban development.
In rural Cameron County, Lambert is already seeing that future. Earlier this year, before the rain soaked the area, Lambert told sugar cane farmers in his district that they would only have one delivery of water instead of two.
To save their thirsty crops, some farmers bought water from neighboring districts for tens of thousands of dollars. Others have removed over a hundred acres of the crop. A few weeks later, the sky opened.
When farmers ask her how much water they can expect to receive next season, Lambert replies that she often doesn’t have an answer.
“This is the million dollar question asked by our farmers. And I have no earthly idea, ”she said.