In South Texas, an aging water system meets a growing population –



McALLEN, Texas (AP) – On a hot afternoon in South Texas, Sonia Lambert looked out over an open-air canal that carries mud-green water from the Rio Grande to nearby towns and farmland, much of it lost the way through evaporation and seepage.

“That will be someone else’s problem,” said Lambert, referring to her upcoming retirement as head of an irrigation district near the US-Mexico border.

In the Rio Grande Valley, a system of canals designed for agriculture more than a century ago still supplies water to the area’s lush farmlands and fast-growing cities. Today, the canals are losing up to 40% of the water they carry – waste that experts say could lead to severe water scarcity in the coming decades as populations grow and climate change exacerbates droughts.

“As this region is getting drier due to climate change, the water supply will be severely reduced,” said Guy Fipps, professor of irrigation technology at Texas A&M University who has been studying the water system since 1998.

State water authorities predict that water needs in cities and towns in the region will double over the next 50 years. For decades, McAllen grew at a dizzying pace, with newcomers moving into a large free trade zone and jobs in healthcare, education, and retail. Between 1990 and 2020, McAllen and the neighboring cities of Edinburgh and Mission increased sixfold to nearly 871,000 people, according to the US Census Bureau. Similarly, the Mexican cities of Reynosa and Matamoros grew across the border after US assembly plants were established in the mid-1990s.

To make matters worse, a 1944 treaty between the United States and Mexico stipulates how the countries share water from the Rio Grande. Mexico is slated to channel 350,000 acres of water into the US each year – enough to supply up to 700,000 households. But it has regularly failed to meet these obligations and has delayed deliveries due to drought, scarce water supplies and a thirsty grain industry in northern Mexico.

The late deliveries are a source of frustration, but water managers and farmers in the United States are quick to recognize a major challenge at home as well: the leaky sewer system that has long been considered too expensive to overhaul by local and state authorities.

The region’s more than 3,219 kilometers of pipelines and canals – around 30 meters wide – are intended for large, infrequent deliveries to farmland. Common measures to modernize and increase the efficiency of waterways – which have been tried to some extent by many counties – include lining clay canals with concrete and more accurate monitoring of water use by farms with meters. Another option comes at a higher price: replacing canals with underground pipelines, which lose much less water and are better suited to supplying cities.

Converting a mile of an open air canal into underground pipelines costs between $ 250,000 and $ 1 million, said Lambert, the irrigation district manager for Cameron County, which remains largely rural. Her district has only been able to put about a fifth of its 402-kilometer-long canals underground in the past two decades, she said.

“It will just be an amount that the farming community could not support,” said Lambert.

Since the early 1900s, a network of about two dozen independent irrigation districts has served the region’s farmers, towns and cities. But when McAllen devoured much of the surrounding farmland, some officials wanted more control over a water district that they say it overcharges the city for water supplies.

But the higher fees charged by city water utilities are often the way irrigation districts pay for sewer repairs, Fipps said. As a result, the water districts that serve larger cities have typically made more progress in upgrading the canals.

Still, the water utilities and farms of the Rio Grande Valley are linked by the same aging system.

With towns and farms drawing water from the same canals, hydrologists and water officials believe that if drought persists, the shrinking volumes of water and low reservoirs of the Rio Grande could eventually create problems for everyone. If there is little water in a canal, a larger percentage is lost through evaporation or seepage. And every share of water is threatened.

Experts already say that the demand for water from the river exceeds the supply.

Small towns that receive relatively small supplies of water could be particularly hard hit during a severe drought, and their irrigation districts have less money to repair or replace canals.

“This is an unusual situation that the agricultural canals are being used to deliver the city water,” said Fipps.

Experts say that over time, the region’s farms will face increasing water scarcity and will be forced to make more difficult decisions, a scenario already playing out in parts of the American West. Some irrigation counties have received state or federal funding over the years through grants administered by the Bureau of Reclamation for repairs, but water managers, farmers, and hydrologists say the money was insufficient for extensive repairs. The Texas Water Development Board predicts that by 2070 the water used to irrigate farms in the Rio Grande Valley will decrease by 36%, largely because more farmland is being replaced with urban development.

In rural Cameron County, Lambert already sees an outlook for this future. Earlier this year, before the rain soaked the region, Lambert told sugar cane growers in her district that they would only get one delivery of water instead of two.

To save their thirsty crops, some farmers bought water from neighboring counties for tens of thousands of dollars. Others removed more than a hundred acres of harvest. A few weeks later the sky opened.

When farmers ask her how much water to expect in the next season, Lambert says she often doesn’t have an answer.

“This is the million dollar question our farmers are asking. And I have no earthly idea, ”she said.


EDITOR’S NOTE – This is the third story in an occasional series that explores the interaction between population growth and climate change.


The Associated Press is supported by the Walton Family Foundation for reporting on water and the environment. The AP is solely responsible for all content. You can find all of AP’s environmental reports at


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