GALT, CA (MPG) - The group tasked with managing local groundwater use questioned Galt officials on Aug. 7 about a well project proposed by the city.

While city officials voiced confidence that the project would not harm nearby water users, multiple Cosumnes Groundwater Authority (CGA) board members were skeptical and disagreement emerged over the potential effects in different levels of the area’s aquifer.

The item was for informational purposes and the board took no official action.

Cosumnes Groundwater Authority is a partnership of several irrigation districts and the city of Galt, which all draw water from the same groundwater subbasin. Cosumnes Groundwater Authority’s goal is to make groundwater use more sustainable, balancing the amount of water different jurisdictions pull out of the basin with the amount that flows in.

Galt City Council in June considered a contract for exploratory work to determine the feasibility and effects of deepening a well near Carillion Boulevard. A structural failure put the well out of commission several months ago. City staff said the project would allow the well to draw on a deeper water source with higher water quality; the current source needs to be treated for arsenic and manganese.

Cosumnes Groundwater Authority Chair Lindsey Liebig-Carter said the groundwater authority had not been properly notified and requested more information. City Council decided to postpone a decision on the item until the city could present to the Cosumnes Groundwater Authority board.

Principal hydrogeologist Sean Spaeth with consulting firm Wood Rodgers said the process would start with the drilling of a test well to 1,500 feet, with sampling to gather data on the groundwater quality and level. The testing and design process is projected to last until mid-2025, after which the project would go to bid.

A presentation said the well would increase the city’s water supply capacity with redundancy to reduce the risks if some wells go offline.

Cosumnes Groundwater Authority Director Gary Thomas of Amador County Groundwater Management Authority pointed to housing developments in planning and under construction in Galt, saying they would increase the city’s water demands.

Galt City Manager Chris Erias said environmental review for developments includes a water element to ensure groundwater isn’t impacted. He later estimated that the city has 3,000 housing units in the development pipeline in the next decade.

Alternate director Herb Garms of Sloughhouse Resource Conservation District said the city pumps water on the east side of town and ultimately releases it from the water treatment plant on the west side, rather than putting the water back into the ground it came from. He said this would worsen the cone of depression.

“The interesting thing about ag is it (water) stays there; it doesn’t go anywhere. Housing pulls it out, sends it somewhere else, and you’re impacting,” Garms said.

Spaeth said the test well would help to predict such effects. He noted that the well would target a deeper level of the basin, which he said is separate from the shallower one that the current well taps. Most area wells pull from the shallower level and, Spaeth said, the shallower level would not be affected by water drawn from the deeper one.

Citing similar projects in the region, with one well tapping the shallower level and another well tapping the deeper one, Spaeth said, “We didn’t see any response as a result of pumping the other. Right now, the current understanding is that, yes, they are hydraulically separated.”

A representative of EKI, a consulting firm that has helped the city document its water resources, disputed that assertion. EKI principal hydrogeologist John Fio described the two levels as “one unit.”

“I don’t know how to quantify that relationship. It can vary. But over time, if you’re pulling down water levels in a lower aquifer that’s not 100% isolated, there’s going to be an impact,” Fio said.

Fio appreciated the plan to drill a test well, which he said would yield valuable data on how water levels might change.

Liebig-Carter said the board would revisit the issue.

“This is the start of the conversation. We have met prior to this as well with the city and we’ll stay engaged and we’ll keep this as a regular update item,” Liebig-Carter said.