On a quiet industrial side street near 41st Avenue and Soquel Drive, the Santa Cruz Water Department has been quietly pumping millions of gallons of water through temporary PVC piping.
Every minute, about 400 gallons flow past pressure gauges and shut-off valves into a 2-foot-high concrete box that marks the top of Beltz Well 12. If a pilot program goes well, this whole system could play a pivotal role in the water security of communities from Aptos to UCSC. Normally, water is pumping out of this well, not into it. As part of the reversal process, engineers went into the well and removed column piping, which now lies in a pile under a plastic tarp off to the side. Two 35,000-gallon tanks sit empty.
Here, the city of Santa Cruz’s water department is in its third round of testing a plan to pump water underground, into the Purisima Aquifer to rest the area’s wells and hopefully provide a new reservoir of water storage—one that could supplement Loch Lomond, the city’s current reservoir up in the Santa Cruz Mountains. The strategy is one of the top options laid out by the 14-member Water Supply Advisory Committee (WSAC) three-and-a-half years ago. The body was formed to look at alternatives to a controversial desalination plant that the city had worked toward for years as a means of building up a limited water supply.
Former members of the committee will join the Santa Cruz Water Commission on Monday, April 1, for a joint meeting to hear updates. The commission is also set to meet with the Santa Cruz City Council on April 23 for another update.
So far, the process of pumping all this water into the ground—aquifer storage and recovery (ASR), as it’s called—is going rather smoothly. As part of the pilot program, engineers have also been pumping the water back out again.
The outlook is similarly encouraging for another top WSAC recommendation: water swaps with the neighboring Soquel Creek Water District, which relies more heavily on the severely overdrafted aquifer than Santa Cruz does.
“It’s a two-headed beast, and we’re working on both of them right now,” Santa Cruz Water Director Rosemary Menard says of the options the city is studying.
Skeptics of these pumping and water-swapping approaches weren’t necessarily wrong when they opined years ago that the whole undertaking would be easier said than done. No one has all the answers yet, and water officials are still working on getting a tweak to local water rights approved by state and federal regulators.
But for their part, critics of desal now look relatively prescient themselves.
A recent UCSC study of a Carlsbad desalination plant found that the operation raised salinity levels more than was permitted, even though the discrepancy had no effect on sea life. More significantly, new regulations call for desal plants to have subsurface intakes below the seabed, instead of traditional ones above the ocean floor. Per the WSAC recommendations, Santa Cruz had already listed desal as an option of last resort, but the City Council has since de-prioritized the idea of a plant even further.
“The requirement is that you have to use a subsurface intake unless it’s infeasible, but there’s no definition of what ‘infeasible’ is,” Menard says. “So you would just have to keep studying and studying and studying to determine whether it was infeasible or not. And at some point, that looked like a strategy that could not get us to any kind of plan that would be permissible and implementable on a time frame that we’re trying to achieve.”
The 2015 WSAC recommendations adopted by the City Council were broken down into three tiers. The top recommendation was aquifer recovery by either the ASR method of pumping water into the well, or by doing “in-lieu” water swaps to share excess winter waters from Santa Cruz with Soquel Creek Water District customers, who rely solely on the aquifer, which is at risk of seawater intrusion, as a way to let groundwater levels rebound. The idea behind the process—sometimes called conjunctive use—is that Santa Cruz should be able to pump water back out in dry summers and during drought conditions.
The second tier in the possible recommendations was indirect potable reuse, which would involve pumping treated wastewater into the aquifer. This approach is what Soquel Creek has chosen to combat its water shortage.
Lastly, the WSAC suggested that, if all else fails, the city might pursue direct potable reuse, sometimes crudely known as toilet-to-tap—assuming that it gets approved by state regulators, which is expected to happen before long. After that, desal would be a last resort.
From the pilot tests, ASR is showing promise. Each stage of the pilot lasts longer than the one before it. In the first round of testing, engineers pumped water into the ground for a day, left it underground for two days, and then pumped it back out. In the third and final round, the city is pumping the water in for a month, and will leave it underground for two months while running tests. If approved by regulators, the engineers will pump the water back into the city’s drinking water supply.
Water Commissioner Engfer served on the WSAC, and he’s optimistic that the commission will be able to solve its shortage with conjunctive use. Santa Cruz might pursue a recycled water project in the future, he says, depending on how bleak things end up looking down the road.
“It happens over time. I’m not dying to spend all my money right now,” says Engfer, an entrepreneur. “We’re going to spend some of our money and wait for more information until the time is right. I don’t know what the future’s going to be.”
WET IN DOUBT
There’s a good reason for water commissioners like Engfer to be talking about the future as if the big decision is really about money. It is about money.
The water department needs major infrastructure improvements, including a new $86 million intake at Loch Lomond and water treatment improvements. Those could have the added benefit of meaning more supply for water customers, but they won’t come cheap. Rates have already risen sharply over the past four years.
As water commissioners look ahead, there are two questions with no clear answers. One is how much water security these aquifer storage programs—including Soquel Creek Water District’s recycled water project—can really provide. The other is how much water the system will need.
The worst drought Santa Cruz ever faced was in 1976-77. A decade later, another drought started in 1986 and ran much longer, although it wasn’t as severe in its intensity. One hypothetical worth considering: What if Santa Cruz suffered a dry spell as bad as the ’76 drought, but it lasted as long as the one in the 1980s and early ’90s?
Soon, water commissioners will look at three models of future climate change, so they can contemplate how various solutions would perform under each climate scenario.
In addition to drought, global warming is expected to bring bigger storms, which could put a strain on local infrastructure. It’s another reason the district is eyeing upgrades.
During the heavy rains of 2017, the Newell Creek pipeline suffered five failures by March. Menard says the system is due for an overhaul.
“Major pieces of the backbone infrastructure have reached the end, or near the end, of their useful lives,” Menard says. “At the same time, we have to do that in a way that makes it affordable for people to have water. It’s a challenge.”