After four years of studying the Lower Rio Grande Valley's vast irrigation and water distribution system, Texas A&M engineers say improving the antiquated system will produce less expensive water than building desalination plants or water pipelines from other areas.
The information Texas A&M developed is now being used by Congress to justify expenditures to rehabilitate the water system. A bill currently in the House of Representatives authorizes a total of 19 irrigation district rehabilitation projects, roughly half the projects needed to upgrade the entire system.
Dr. Guy Fipps, a Texas A&M professor and Extension agricultural engineer, said that of the one million acre-feet of total water currently used annually in the Valley, as much as 50 percent to 60 percent of that amount is lost to seepage, evaporation and spills in the distribution networks and to inefficient on-farm irrigation practices. The water losses exacerbate a years-long Valley drought and perilously low water reserves.
“If every rehabilitation project were implemented as recommended, we're looking at saving about 175,000 acre-feet of water per year in the distribution networks and another 225,000 acre-feet per year at the on farm level,” Fipps said.
“That 40 percent savings is a significant amount of water and could be used for both improving ag production here, plus meeting the future needs of industries and cities in the region,” he said.
When Fipps began evaluating the Valley's water distribution network in 1998, he had little to work with. The only map of all the distribution systems was developed in the 1950s, and there was scant information on current conditions.
“So,” Fipps said, “my team, including Eric Leigh, and I mapped the distribution networks, and worked with the irrigation districts to update their map. We assessed the current conditions of the infrastructure, and based on that information developed water-saving potential estimates.”
Two Texas A&M departments, agricultural engineering and agricultural economics, are now providing direct assistance to Valley irrigation districts in completing applications to access federal funds when available for district rehabilitation.
Fipps said system rehab will include lining dirt canals or replacing them with pipelines, installing water measurement and metering structures, installing new gates with automatic gate control systems, eliminating spills at the end of canals by recirculating and reusing that water, and building reservoirs and storage facilities within irrigation districts to help improve water movement.
The cost? Fipps said original estimates of $200 million were probably too low and likely will be closer to Mexico's estimates of $400 million to $450 million to rehabilitate the water system on their side of the Rio Grande. This figure, Fipps said, is still less expensive and more reliable than building desalination plants or piping water in from other parts of Texas.
“We'll be working with Dr. John Robinson (agricultural economist at the Texas A&M Agricultural Research and Extension Center at Weslaco) in the coming months to update the cost estimates of rehabilitation, but I suspect it will be closer to Mexico's estimate.”