Effects of climate change — heat, more droughts — could place aquifer at risk.
Report: Climate change, population growth could threaten water supply in next 50 years
The Edwards Aquifer could be at risk in the next 50 years as a result of warmer temperatures and more frequent and severe droughts, compounded by population growth.
“These climate change impacts will be exacerbated in central Texas’s rapidly urbanizing regions, as increasing impervious cover will affect water quality and rates of runoff and recharge,” stated the Fourth National Climate Assessment, a 1,656-page report released by the federal government.
Officials in California, Florida and other coastal states are increasingly concerned about heat, sea levels and severity of storms in a warming world, said Doug Melnick, the city of San Antonio’s chief sustainability officer.
But San Antonio, too, is vulnerable to the effects of climate change, Melnick said.
Already, extreme floods in San Antonio have prompted authorities to redraw flood maps and demolish homes, includes those along Salado Creek on the East Side that were ravaged by a 1998 flood and others along Barbara Drive on the North Side that were damaged by a 2013 deluge.
“We’re seeing discussions as we speak, statewide and nationally, about adjusting 100-year and 500-year flood zones,” Melnick said. “That’s going on now, and that really is the direct result of climate change.”
Officials of the Edwards Aquifer Authority are preparing to quantify the potential impact of climate change on the severity of droughts in the region. But the authority said it would be “premature” to predict “a degradation of habitat for species of concern,” an outcome projected in the National Climate Assessment released last month.
Studies have found that conservation measures adopted in 2012 “are enough to maintain spring flows that are critical to the habitat” of fountain darters
and other endangered species, “even if a drought as severe as the 1950s was repeated,” EAA General Manager Roland Ruiz said.
“What is more probable is that these conservation measures would need to be implemented more frequently to maintain critical spring flows in a warmer climate,” he said.
For homeowners, that would mean more frequent limits on lawn watering. San Antonio currently is under year-round watering rules, which allow sprinkler use any day before 11 a.m. and after 7 p.m.
San Antonio’s 1947-1957 drought was surpassed in intensity by a 2008-2014 dry spell, according to the new federal climate report.
“What made 2011 so bad was the long streak of record-breaking temperatures,” Ruiz said. “If not for having a moderately wet 2010, this drought would have rivaled the 1950s drought.”
In its 2017 Water Management plan, which seeks to project conditions more than 50 years into the future, the San Antonio Water System created a worse-case drought scenario based on past droughts.
“The lessons from every drought continue to be that managing our long-term water future is a mixture of having adequate supplies and continuing to commit to conservation,” said Donovan Burton, vice president of water resources and government relations at SAWS.
From 1982 to 2016, San Antonians reduced water use from 225 gallons per person daily to 117 gallons, according to SAWS. Through leak-detection technologies and conservation measures, the utility hopes to further lower consumption to 88 gallons daily by 2070.
But SAWS also expects to serve 1.4 million more people by then, for a total of 3.2 million. After reducing reliance on the Edwards from 70 percent of its water supply in 2000 to 42 percent today, SAWS aims to further reduce use of Edwards Aquifer water to 31 percent by 2070.
It is also adding an important new source of supply: The 142-mile Vista Ridge pipeline is scheduled to start delivering water from the Carrizo-Wilcox Aquifer in Central Texas in April 2020.
“The diversification of San Antonio’s water supply is key to ensuring the city has the appropriate supply of water to meet the needs of a growing economy,” Donovan said.
The SAWS water plan predicts the possibility of a small “supply gap” in 2050, amounting to 5,757 acre-feet. But the utility says it could expand its brackish water desalination plant or the Carrizo Aquifer project to close the gap.
Another key concern in the federal climate report is that urban growth will result in “increasing impervious cover” — buildings and pavement — reducing the amount of water that seeps into the Edwards Aquifer through porous limestone formations.
The city’s climate action and adaptation plan is scheduled for release in draft form next month. City Council is scheduled to adopt the plan in April. The document is expected to focus heavily on reducing greenhouse gas emissions and mitigating temperature increases. It also will also include a water and natural resources component.
The plan may include recommendations for “improvements to urban landscapes, stormwater management and improvements to soils to better store carbon and retain water — all of which could help protect the aquifer,” the EAA’s Ruiz said.
During the last drought, an EAA program paid farmers to the west of San Antonio not to irrigate, leaving water in the aquifer. In addition, the SAWS Aquifer Storage and Recovery facility south of the city — the nation’s largest groundwaterbased storage facility — currently holds 170,000 acre-feet, more than two-thirds of the utility’s annual demand.
Ruiz noted that the new federal report projects increases in annual average temperatures in the Southern Great Plains of 3.6 to 5.1 degrees Fahrenheit by 2050, and 4.4 to 8.4 degrees by 2100. That would raise evaporation rates, reducing aquifer recharge. But the report noted that the types and frequency of severe weather were difficult to predict, Ruiz said.
“There is some evidence that local-scale severe storms can become worse and produce more rainfall, but periods between storm events could be drier — in part due to the higher temperatures,” he said. “So, stronger storms could at least partially offset some of the effects of higher temperatures.”
practices for fighting wildfires.
Their efforts, funded by a grant from the Federal Emergency Management Agency, focus on smaller departments that might not have the resources to handle a raging wildfire.
That’s important because those firefighters are often on the front lines before backup can arrive.
“Those are the ones that are going to be mostly impacted in the difficulty of getting resources in quickly,” Swan said.
The association has tested their training in Lewiston, Maine, and Colorado Springs, Colo., prior to their stop in San Antonio.
They chose San Antonio after Hood expressed an interest. Hood said the department has “a robust amount of resources,” including brush trucks and water tankers, to fight wildfires but it’s important to continually train because the dynamics of fighting a wildfire differ significantly from a structure fire.
“An urban interface fire is probably a lot more challenging in the big picture than most structure fires we fight on a day-to-day basis,” Hood said.
Eleven instructors — including the incident commander for the Camp Fire in California — conducted the training, which included 32 hours of online and classroom instruction followed by hands-on drills and role-playing scenarios. Sixty San Antonio firefighters took part.
Residents of Roseheart allowed firefighters to block off streets Thursday to put their skills to the test.
The simulations were designed to be as realistic as possible. Instructors were cast as residents, and yellow cue cards were placed throughout residents’ yards to represent obstacles or emergencies, including kids taking selfies, an elderly man unable to evacuate and power lines in the path of the fire.
“We try to put a little bit of real life into it,” Swan said. “There’s a lot of emotion. We want to push some buttons on these guys so they think, ‘Oh, this could be real life.’ ”
‘It’s about saving lives’
Some of the obstacles were built to test the crews. Swan said many firefighters, when arriving at a place where four houses are burning, would try instinctively to douse the fire, rather than pull back to make a fire wall that could stop it from spreading.
As one instructor says: If you save one house, you’ll lose 10.
“We want to break that muscle memory,” Swan said. “We want to show them, ‘You don’t necessarily have to do it this way. You can do it this way and be much more efficient and save more homes.’ ”
Hood said the benefits of the training were threefold.
“It’s about saving lives of the citizens, but it’s also about saving the lives of my firefighters, to make sure that they’re in the perfect position so that they’re going to be successful and they’re going to go home at the end of the shift,” Hood said. “It is also about saving the valuable properties that could be lost in this situation.”
“The citizens, the firefighters and then the property.”