Record-low water levels in the Bexar County portion of the Edwards Aquifer could signal trouble for San Marcos’ supply.
The Edwards Aquifer pool, which provides most of Bexar County’s water, started off the year at 640.7 feet, its lowest level in more than five decades. Lynne Fahlquist, public information officer at U.S. Geological Survery (USGS), said the amount of water the San Antonio area receives is a good indicator as to how much will end up in San Marcos.
“Generally, as groundwater levels drop in the San Antonio segment of the Edwards Aquifer, spring flows at Comal and San Marcos springs also decline,” Fahlquist said.
The most recent water flow readings for the San Marcos Springs are 172 cubic feet per second, compared to the average 184 cubic feet per second, according to USGS water data. Some fear that because of the declining water supply, current water restrictions in San Antonio may soon exist in San Marcos, said Tom Taggart, City of San Marcos executive director of Public Services.
“These are pretty scary numbers in a sense,” Taggart said. “This could indicate that we’re going to be in much deeper drought restrictions toward the summer and drier periods of the year.”
San Marcos is currently in stage two of water restrictions. This means residents are permitted to water their properties with a sprinkler once a week on a designated day before 10 a.m. or after 8 p.m., according to the city’s website.
The city went from more restrictive stage three regulations down to stage two Nov. 13, 2013 due in part to the surge of rainwater in late October. However, recent droughts may force the city to return to stage three restrictions, only allowing sprinkler irrigation every other week on designated days between 6 to 10 a.m. and 8 p.m. to midnight.
“We’ve been hovering a few feet above stage three for a while now,” said Jan Klein, City of San Marcos Public Services Conservation coordinator. “And we’re predicting to go back to stage three restrictions in springtime once people start irrigating.”
The irrigation of cropland typically begins at the end of February, Taggart said. Since the water San Marcos receives stems from Bexar and Comal counties, the drought levels in San Marcos depend on how much rain those areas receive, Taggart said.
“The aquifer tends to flow west to east,” Taggart said. “So the J-17 well (the Edward’s Aquifer indicator) level measures the aquifer level in a path that flows to us.”
Once the irrigation begins, water consumption increases significantly, said Dianne Wassenich, program director for the San Marcos River Foundation. Variables such as the warm temperatures and wind can cause the cropland to lose moisture quicker.
“Dry spring winds in March are very damaging to plants,” Wassenich said. “People use a lot of water on their lawns when that happens, as well as crops.”
The Edwards Aquifer Authority (EAA) monitors the water levels and drought conditions all around southwest Texas, according to the EAA website. They set the water restrictions for each county. All counties in the Edwards Region are at a stage two water restriction or higher. The majority of the water the city consumes does not come from the aquifer, but from Canyon Lake and other surface water sources.
“With current drop restrictions with the EAA we are required to reduce withdraws from the aquifer, and the City of San Marcos, at this point in time, is using very little of our aquifer water,” Taggart said. “We’re almost 90 percent on surface water at this point.”
The coming season will decide how strict the water restrictions will be for the rest of the year. It depends on the amount of rainfall the surrounding counties receive, and so far, the outlook is not promising, Wassenich said.
“We just hope we get some spring rains, but are not counting on it,” Wassenich said. “There is a prediction mid-summer will see a shift in weather, to bring us an El Nino pattern, which tends to be wetter for Texas. We hope it happens.”