The Paso Robles Groundwater Basin lost another 81,800 acre feet (AF) of water storage this spring compared to last spring—the fourth consecutive recorded decline in aquifer levels since 2020 and a continued sign of drought and overpumping, according to SLO County Groundwater Sustainability Director Blaine Reely.
“We’re pumping more groundwater, significantly more groundwater, out of the basin, especially in these drought years, than is being recharged,” Reely told New Times.
The spring-over-spring snapshot is a first for SLO County, which typically does its Paso groundwater measurements in the fall of each year.
Last fall, the county saw a 62,300 AF decline in the Paso basin compared to 2020, and an 80,8000 AF decline in 2020 compared to 2019. For context, 1 acre foot of water is roughly equivalent to an eight-lane swimming pool that’s 10 feet deep.
Reely presented those numbers to the Paso Basin Cooperative Committee on July 27 but added a caveat: The two spring measurements didn’t occur on the same day or week, which means they could be skewed by varying levels of irrigating during their recording.
A heat map of the spring-to-spring decline shows that the steepest drop in water levels was in the Shedd Canyon area near Highway 41, about halfway between Creston and Shandon. Another area of sharp decline was in the northeast area of the city of Paso Robles.
But again, Reely advised the committee not to draw too many conclusions from the map.
“I would say that heat map is probably not a completely accurate depiction,” Reely later told New Times. “That area [Shedd Canyon] has alfalfa and that irrigation had started a few weeks before we got out there [this spring]. That heat map is probably not as problematic as it might look.”
Acknowledging that the existing tools to track Paso groundwater are flawed, Reely said he’s optimistic that the situation will be different come next year. That’s thanks to a $7.6 million state grant, which will allow Paso officials to grow and improve upon the basin’s well monitoring network.
“Our monitoring network is still pretty sparse and we have a lot of gaps,” Reely told the Cooperative Committee on July 27.
A $1.4 million share of the grant will help facilitate not only the addition of new wells to the basin monitoring network, but the installation of instruments to track water levels in real time. Those continuous measurements could then supersede the once or twice per year readings that were historically used.
“This allows somebody to sit at a desk with the computer in front of them and receive the data real time,” GSI Solutions consultant Nate Page told the Cooperative Committee. “With better data, you can make more accurate basin water budget calculations. You can start to understand well interference in real time, and that could be real important if you have some domestic wells going dry. What are the stressors?”
Reely said basin leaders are working right now with landowners to negotiate the inclusion of their wells into the current roughly 100-well monitoring network. The next steps are to procure the instruments for real-time tracking and decide where to install them.
“With that kind of data, and these guys’ brains, we can really understand to a much greater degree what’s going on in the basin than we do now,” Reely told committee members. Δ
This article appears in Aug 11-21, 2022.
The basin did not loose 81,800 acre feet of storage. Possibly it’s been pumped down that much, possibly. The modeling makes no sense and seems more like a good guess at best. Regardless the storage space is still there, however the water may not be.