Rains help to ease local drought
Near-normal precipitation has lightened arid conditions as the area welcomes rising aquifer levels and other markers
The San Antonio area’s drought is not over, but things are getting better.
Thanks to a return to nearnormal rainfall totals, drought conditions in Bexar County and across much of the region have eased considerably in the past two months, according to data from the U.S. Drought Monitor. Back on April 4, nearly all of Bexar County — about 80 percent — was experiencing exceptional drought, according to the U.S. Drought Monitor. That is the most severe categorization of drought and would typically occur just once or twice in 100 years.
Fast forward to this week, and none of Bexar County is in exceptional drought, according to the monitor’s new data. In fact, most of the county — about 58 percent — is now in the two least-severe drought categories.
Similar improvements can be found throughout the region and across Texas, according to the monitor. Currently, 40 percent of Texas is drought-free and only 16 percent of the state is in one of the three most severe categories, the monitor’s data shows.
Water levels in the Edwards Aquifer — a limestone cavern system that spans 3,600 square miles and provides water for more than 2 million people — have risen to their highest levels in nearly a year. The aquifer’s springs feed a number of local streams, including the Guadalupe River and the San Antonio River.
While those are positive developments, they don’t mean the drought is over, experts say. The drought’s impact continues to be felt throughout the region, with lower-than-normal water flow in many streams and springs, low water volume in lakes and lingering damage to trees and other plant life.
Last year was one of the driest on record for San Antonio, with rainfall 20 inches below normal. As of Thursday, rain gauges at San Antonio International Airport had recorded 11.84 inches of rain this year. That’s already more than the 11.51 inches that fell at the airport all last year — but it’s still below the historical norm of 12.9 inches, said Paul Bertetti, senior director for aquifer science research and modeling for the Edwards Aquifer Authority, the agency that manages the aquifer.
“People have a perception right now that we’ve had a lot of rain, and we have relative to 2022. But we’re still about an inch below average,” Bertetti said. “We had such a deficit, especially in 2022 and the end of 2021, that it will take some time to make up for that deficit.”
The Edwards Aquifer’s water level was at 647.1 feet on Friday. On April 4, the water level was at 634.8 feet. So in not quite two months, it has risen 13 feet. The current 10-day rolling average is 647.6 feet. If the 10-day rolling average rises above 650 feet, the Edwards Aquifer Authority could choose to further ease pumping restrictions from Stage 2 to Stage 1.
That swift rise in the water level is not surprising, Bertetti said, because May and June tend to be among the wettest months of the year for the area. And even with the recent rains, the aquifer’s water level remains well below the historical norm, he said.
“The median water level for this time of year is 665 feet or so,” Bertetti said, “so we’re still nearly 20 feet below the median coverage for this time of year. Yes, it’s great that we’ve had improvement. But we’re still in Stage 2 for a reason, because of the lack of rainfall for the last 18 to 24 months.”
With the year’s hottest
months ahead, it’s likely the aquifer’s water level will drop again during the summer, Bertetti said.
What the aquifer needs is sustained above-average rainfall over the Edwards Aquifer’s recharge zone, or a major rain event such as could be generated by a tropical storm, Bertetti said. The recharge zone is a roughly 1,200-square-mile swath of land stretching from Kinney County up to Williamson County in which the structure of the Edwards limestone formations allows large quantities of water to flow into the aquifer.
One of the challenges for the San Antonio region, and for Texas as a whole, is replenishing the
moisture in the soil, said Richard Heim, a meteorologist with the National Centers for Environmental Information, which is part of the National Oceanic and Atmospheric Administration.
“The big picture is the two to three years of dryness and drought pulls moisture out of the ground. The recent rain will replenish the top layer, but it takes time to get to the deeper layers of soil and it takes even longer for it to get to the groundwater,” said Heim, who is also one of the authors of the U.S. Drought Monitor.
Bertetti compared the region’s soil to a sponge that’s been allowed to dry out.
“One of the things that we look at and the U.S. Drought Monitor network looks at is: How dry is the soil system?” he said.“if I have a really dry sponge and I pour water on top, takes time for (the) sponge to recover enough to transmit water through it. A sponge that’s already saturated is much more efficient at passing water through. We’ve dried out the upper portion of the soil and the bedrock, so it needs to recover so it can more efficiently recharge and pass water through. We’ve got to re-saturate the soil and the uppermost bedrock so that part of the recharge zone is functioning.”
Both Heim and Bertetti said
indicators suggest a shift is underway from the global climate phenomenon La Niña, which causes drier and hotter weather, to El Niño, which typically produces wetter and colder weather.
Forecast models from the federal Climate Prediction Center project roughly normal rainfall amounts for Texas in the coming months, Heim said. That would be a significant change from last year, which was one of the driest on record.
“My guesstimate for Texas,” Heim said, “would be some relief and slow, gradual recovery from drought.”