South Texas reservoir levels are low and keep dropping

WESLACO  —  With reservoir levels dropping, South Texas growers should be especially mindful of their irrigation practices, according to Dr. Juan Enciso, an irrigation engineer at the Texas A&M AgriLife Research and Extension Center at Weslaco.

Dr. Juan Enciso, an irrigation engineer at the Texas A&M AgriLife Research and Extension Center at Weslaco, is shown with a computerized surge-irrigation system. (AgriLife Communications photo by Rod Santa Ana)

“By nature, growers are outstanding stewards of our natural resources, but with water levels as low as they are, more than ever growers should be reminded to be very cautious about how and when they irrigate,” Enciso said.

The lakes at Amistad and Falcon dams, which provide water to farmers and municipalities downriver, are relatively low, according to Erasmo Yarrito Jr., Rio Grande watermaster with the Texas Commission on Environmental Quality in Harlingen.

“We’re at a combined 44 percent of capacity, which is down considerably from the 73 percent we were at last year at this time,” he said. “It’s nothing to panic over because we’re sitting on about a year’s worth of water needs, but we could use some inflows from rain into the watershed, which have been slow in coming this year. And we need to curtail water use.”

With Falcon Lake at about 19 percent of capacity, Yarrito has been moving water from Amistad to Falcon to prepare for water demands from growers who will be planting in the fall and again next spring. Amistad is currently at about 54 percent of capacity.

“So far, Falcon is up by over a foot after about six weeks of moving water from Amistad,” he said. “What we keep in Amistad will be for any emergencies we might have, but conservation by both municipalities and growers goes a long way in helping the situation.”

Fields should never be left unattended when irrigating, Enciso said.

“All irrigation should be supervised because it’s so important to avoid any spills,” he said. “Try to avoid runoff. Furrows should be blocked off at the lower end of fields, and if we receive any rainfall of more than 2 or 3 inches, growers should delay irrigation.”

Growers also need to keep in mind that crops reach a point in their growth when more water doesn’t help, he said.

“Some crops don’t need irrigation when they reach physiological maturity. Any water they receive after that is wasted because it will not increase yields. In fact, most crops won’t lose yields if you apply 20 to 25 percent less water than the requirements for that crop.”

Enciso said growers who furrow irrigate can save water by irrigating alternate rows.

“Our studies show that growers can save 30 percent of their normal water usage by irrigating alternate rows,” he said. “It reduces vertical infiltration and leaching of fertilizers, substantial amounts of water are saved, and yields don’t suffer.”

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