Digging 1,000 feet and purifying sewage: How Soquel Creek district is replenishing water supply amid drought

The Soquel Creek Water District, despite its name, draws no water from Soquel Creek or any other creeks — it relies entirely on the Santa Cruz Mid-County Groundwater Basin to serve its 40,400 customers in Aptos, La Selva Beach, Opal Cliffs, Rio Del Mar, Seascape, Soquel, and portions of Capitola.

And that single source has contributed to a water sustainability problem for years.

Despite residents significantly reducing their water use since an emergency status went into effect seven years ago, prior decades in which more water was taken out than was replaced by rain has created a deficit that has been hard to replenish as drought conditions have persisted. Worse still, the depleted aquifer allows seawater to intrude, ruining it for potable use.

The city of Santa Cruz enacted stage one restrictions (the lowest level, in which customers receive a water allotment but no penalties are applied for exceeding it) last week in the face of a bad water year. Meanwhile, Soquel Creek has been in a “stage three water shortage and groundwater emergency” since 2014.

Under these restrictions, residents served by the district are never allowed to use sprinklers between 10 a.m. and 8 p.m., and restaurants in the area can only give customers drinking water upon request.

So what is the district doing to combat this problem? Purifying wastewater and drilling wells, up to 1,000 feet deep, to pump it into the aquifer, hoping to replenish the long-depleted groundwater reserve and fend off saltwater intrusion.

If it works as planned, it will save the district from even stricter water restrictions, and have positive implications for the county’s other water districts.

Here’s a deeper look at the project:

The unlikely solution: sewage

“Pure Water Soquel” is the Soquel Creek Water District’s ambitious plan, years in the making, to take wastewater from the Santa Cruz wastewater treatment plant, pipe it to an advanced treatment plant that will be built in Soquel, purify the wastewater to drinking water standards, and send it through deep wells into aquifers to refill the groundwater basin.

The project’s estimated cost is about $90 million, and funds are coming from a mix of grants (including $50 million from the State Groundwater Resources Board), and low-interest loans from the state’s Seawater Intrusion Control Loan Program, and the federal EPA’s Water Infrastructure Finance and Innovation Act Program.

The process is called “indirect potable reuse,” and has been used for decades in Southern California, Texas, and other drought-ridden areas in the western U.S.

The district is now nearing completion of the project’s first stage, the drilling of three wells where treated wastewater will be injected into the aquifer.

The wells range from 500 to 1,000 feet deep. Drilling of the third and final well, located on Monterey Street in the Cliffwood Heights neighborhood of Capitola, has just been completed.

Decades to get to implementation

The basin has been overdrawn — that means more water is coming out than going in — for decades. It was officially designated as “critically overdrafted” in 2014.

As more and more water is withdrawn before rain can replace it, not only does the overall amount of water available decrease, but it opens up space for seawater to intrude. The district has known that some action was needed since the 1980s.

“We’ve been monitoring, we’ve been doing conservation,” said Melanie Mow Schumacher, the district’s special projects communication manager.

Several solutions including importing water from elsewhere, trying out desalination, or actually taking water from Soquel Creek, were considered. For decades the district has been stuck in “study, evaluate, repeat, study evaluate repeat,” Schumacher said. “This is the first time when we’ve been able to get to implementation.”

The treated wastewater will help refill the basin and keep saltwater out. Initially, 25% of Santa Cruz wastewater will be diverted for reuse, but if needed it could scale up to 50%.

Impacts beyond the Soquel Creek District

The technology could eventually also be used to help with water shortages in the city of Santa Cruz; the Santa Cruz water systm is considering implementing the same technology to combat water shortages.

"(Soquel Creek) is using about half of the effluent supply available,” said Rosemary Menard, the city’s water director. "(There’s potential) for us to develop that other part for some part of our resource portfolio.

Replenishing the Santa Cruz Mid-County Groundwater basin through Soquel Creek Water District’s new wells will also have implications beyond the district: the city of Santa Cruz, many private wells, and the central water district also rely on the basin. The Pure Water Soquel project will keep the looming threat of saltwater intrusion at bay for them too.

After the recharge wells are completed, the next step is construction of the pipelines to bring wastewater from the Santa Cruz treatment plant to the new, advanced wastewater treatment plant that Soquel Creek Water District is building on Chanticleer Avenue. Construction of that facility will begin in the fall, and groundwater recharge is expected to begin in 2022 or early 2023.