.The Surprising Complexity of Water Transfers

Here’s a bit of somber news for the politically savvy, H20-loving Santa Cruzans who had hoped to see water transfers last winter.

Those water swaps, which didn’t materialize last year, probably won’t this winter either, Taj Dufour, engineering manager for Soquel Creek Water District, told the Santa Cruz Water Commission Monday, Dec. 5.

There’s a number of questions about conjunctive use—the process of the Santa Cruz Water Department sharing water with Soquel Creek Water District, and vice versa, during dry years and months when one agency has more supply than the other.

The idea, borne out of the Water Supply Advisory Committee (WSAC), is for Santa Cruz to share excess river flows with Soquel Creek Water District during rainy winters, and for Soquel Creek to share its groundwater with the city during dry summers. But staff members from both Soquel Creek Water District and the city have been drilling down into difficult questions, including the possibility that the agency’s water supplies may react badly—either with one another, with the pipe mains, or with homeowners’ individual plumbing systems.

The worst-case example of what can go wrong when pumping river water into an unfamiliar pipe system can be summed up in two words: Flint, Michigan. That, of course, is where officials infamously sent Flint River water down old pipes, corroding them and creating an epidemic of health problems.

Here in California, water customers in both Davis and Fresno have run into water quality issues and pipe problems stemming from similar projects.

The concern in Santa Cruz County is that the two water supplies might clash if their pH, alkalinity or mineral makeup doesn’t match up. There could also be issues with sending water flowing down these old pipes in the opposite direction it has been moving in for years.

Water Commissioner Andy Schiffrin wondered aloud if the competing water chemistries from two neighboring districts might be a “fatal flaw” for any hopes of a water transfer.

Schiffrin noted that the district only represents half the water customers in the Purisima Aquifer basin. And if engineers inject Santa Cruz water directly into the aquifer—a possibility that experts are exploring—Schiffrin worries that the districts could open themselves up to liabilities. Private well users who share the basin, like Cabrillo College and Seascape Golf Club, could possibly have chemical reactions with that city-slickin’ water too, he suggested, even if Soquel Creek customers don’t.

These are the types of questions engineers are trying to answer as they explore the recommendations from the WSAC, which the Santa Cruz City Council created in 2014 while looking for alternatives to plans for a controversial desalination plant.

Although the future looks murky now, they hope to have better estimates by mid-2018 on how feasible water transfers would be, as well as the price tag. Monday’s meeting was one of many progress reports in a several-year stretch of careful studies.

Commissioner Doug Engfer suggested a successful conjunctive use program in the Placer area might make a nice case study for what to do. “That’s not to say it would work here, but it might. I want to think they were good more than lucky,” he said, “and maybe there’s some positive lessons we can learn.”

Outside City Hall on a meeting break, Scott McGilvray, a Live Oak resident, mentioned he’s “encouraged” by all the staff members’ hard work, and staying optimistic about water transfers.

“We’re on the right path. I think they’re asking the right questions,” says McGilvray, who likes conjunctive use partly because it’s cheaper to operate than backups like recycled water. “I think they have a sense of urgency about it.”