Everyone seems to agree Santa Fe and the surrounding region are enjoying the benefits of a wet, snowy winter and a robust spring runoff, leading to fast-moving waterways and nearly full surface reservoirs.
But below ground in many areas of the state, including Santa Fe, is a vast array of smaller reservoirs known as the aquifer system — an underground layer of water-bearing rocks and fractures that draw in and keep water that seeps into the ground.
It’s a system that can pay off in infiltrating “thousands of acre-feet a year” to the surrounding area, said Claudia Borchert, sustainability manager for the county of Santa Fe’s Public Works Department.
But the recharge of an aquifer is much more complex than you might think, she told an assembly Friday during the 2019 Next Generation Water Summit at the Santa Fe Community Convention Center.
“The recharge does not occur everywhere equally,” she said.
That’s because the aquifer system depends on a complex set of circumstances to work in its favor. Those actions include the nature of the precipitation — a torrential rainstorm of 20 minutes versus an hourslong snowstorm, for example — the wet area of the waterways and the underlying geology below the ground.
And, she said, the “tools we use to measure streambed infiltration at greater depth … are still pretty crude.”
The vagaries of the aquifer system can be seen above ground in Santa Fe, where it’s possible to view the Santa Fe River running fast and sometimes high along Canyon Road and along East Alameda Street — only to suddenly dry up west of St. Francis Drive. The reason, Borchert said, is because the river begins infiltrating the ground below, in a place where the aquifer system likely benefits from the runoff.
In a wet year like this one, city wells — which make up part of the city’s water source — are less likely to have to pump the ground for water, thanks to the abundance of surface water, she said. For example, earlier this week city officials reported the two city reservoirs, located in the watershed above the city, were 73 and 96 percent full.
“If more water is infiltrating than we are taking out, then the aquifer is recharging,” Borchert said.
The question that remains, she said, is to what degree they are recharging.
Stacy Timmons, hydrology program manager for the New Mexico Bureau of Geology & Mineral Resources housed at New Mexico Institute of Mining & Technology, said Santa Fe is “lucky” to be located in a region with “hundreds of feet of aquifer below the area.”
She said most years, about half of the state’s water supply comes from groundwater and that “years with more surface water are years when you get more recharge in the aquifer system.
“We get far more recharge in years like this where we have snowpacks that melt slowly, and infiltrate into the arroyos and drainage ditches, than we do when we get monsoons that don’t infiltrate as well because it’s coming down in torrents and moves away quickly,” she said.