It’s a dry year. There was barely four inches of rain from January to June. It’s also the second year that the San Joaquin Water Conservation District has no water to sell, despite its written promise of 20,000 acre-feet of water each year. That leaves the district with virtually no way to bring in money.
Many growers have no choice but to pump their own water out of the ground for irrigation.
It’s times like these that people start thinking about groundwater banking.
Several water districts in San Joaquin County — including two that serve customers and growers in the Lodi area — are in talks with East Bay Municipal Utility District to create a joint authority groundwater banking project.
The upside? A consistent supply for growers. Recharging the groundwater basin. Income for the water district that manages incoming and outgoing flows.
The downside? Getting at least four politically charged water authorities to work together on a project where profits and water supply are on the line.
The issue came up in a memo discussed at a Thursday morning meeting of the Woodbridge Irrigation District. Staff from Stockton East Water District were there to share their perspective. On the table are ideas for all groups to bank some water, and all to take it out. No limits have yet been set on how much, or where the water can be sent.
Groundwater can be banked in a few different ways. One method involves drilling a hole down into the aquifer — like digging a well — and pouring water in. But drilling is expensive.
The preferred way is to find an area that drains well, whether it’s agriculture land, an out-of-use soccer field or an open area of pastureland. The zone is surrounded by berms and flooded to create a pond. Then officials just wait for it to drain under the earth’s surface.
Some water will evaporate, and some will be used up by plants or weeds, but about 95 percent gets down to the aquifer. There is a lack of control once the water is under the surface, but it’s possible to research how the water will flow before dispatching it.
For example, say a farmer has 100 acres of row crops in a field. After harvest, a water district or banking authority might offer to pay them to lease the land for 60 days. The land is flooded, and about a foot of water a day will trickle down to the aquifer. After 60 days, 6,000 acre-feet of water is stored and can be retrieved later with a drill.
The aquifer is not a giant underground lake. Instead, water settles in among the soil and the rock fissures and builds up over time. The water comes from rain, snow melt and even the weight of the Mokelumne River rushing over the land.
The idea under consideration is to try banking about 4,000 acre-feet of Mokelumne River water in San Joaquin County, to see if it’s possible and how well the water stores. The memo on Woodbridge Irrigation District’s agenda was just to get the idea circulating. There is no timeline or pricing set.
EBMUD would eventually like to store up to 14,000 acre-feet, but this round will likely use less than a third of that amount.
Gerald Schwartz, ombudsman for EBMUD, said projects like this can make a great source of revenue for any group who can get in on managing it.
“If it’s a county project, they have the say in who the partners are going to be,” he said. “Working together is a lot better than fighting.”
In 1998, Stockton East Water District stored 100 acre-feet of water in the ground for two years as a research test, and pumped out 300 acre-feet before hitting the original groundwater.
If stored surface water is left in the aquifer too long, it will mix in with the native groundwater and change its balance of minerals. It can take years for any stored water to actually reach and improve the water table.
This 4,000 acre-feet water storage test will require more land, time and money than the Stockton East project.
“The reason this project is so attractive to us water districts is we can’t afford to do it ourselves,” said Kevin Kauffman, a consultant with Stockton East.
This project is also special because it involves so many groups.
“You’ve really got East Bay MUD willing to continue to talk to (San Joaquin) entities to reach mutually beneficial conclusions,” Kauffman said.
Joe Valente, president of the North San Joaquin Water Conservation District, said his district is definitely interested in the project, but it’s too early for any certainty.
“One of the sources for the water would be off the Mokelumne, and we have that ability, so we could be in a good position,” he said. “As a county we have to figure out how to do something so we’re more consistent in providing water.”
It’s a big step for the county, but not such a major matter for the City of Lodi. Public Works Director Wally Sandelin said that since Lodi is takes 6,000 acre-feet out of the river instead of groundwater, they are less dependent on any activities with the groundwater basin.
The groups also have to define the rules for where the water can go when it’s removed from storage to supplement a dry year of low flows.
One major obstacle is the groundwater ordinance, as no water is allowed to be exported out of the county. If EBMUD is pulls water out of storage during a dry year, they may send it anywhere in their district, which goes beyond San Joaquin County. But since it’s surface water being stored, not true groundwater, that rule may not apply.
Officials at Stockton East expected EBMUD to want to use their recharge station, since it’s already built. But the site is four miles from the river, and the water would have to be pumped over.
Andy Christensen, general manager of Woodbridge Irrigation District, thinks the pilot project will not be a demo at all, but the whole project. He says the North San Joaquin Water Conservation District deserves to be a major player in this.
“North San Joaquin needs a shot at it. The state is begging them to bring a banking project forward,” he said.
Bill Stokes, president of WID, wasn’t keen on the idea of sending local water out of the area, if that’s what EBMUD chooses to do with water pulled out of storage.
“I don’t think this board will ever agree to export Mokelumne water out of the Mokelumne aquifer,” said Stokes. “We won’t get this if we bank outside, but bank here and we can do it.”
Contact reporter Sara Jane Pohlman at email@example.com.