Santa Cruz, Soquel Creek water propose pilot extension
The program launched in 2016, but water staff say more data is needed
SANTA CRUZ >> The Santa Cruz City Council is poised to approve a 5-year extension between the City and Soquel Creek Water Districts on a pilot program that would funnel excess surface water to Soquel Creek during winter months, in hopes of bolstering overdrawn groundwater supply there.
That surface water on average, is projected be around 115 million gallons delivered by Santa Cruz Water to Soquel Creek during the wet season, which would take strain off pumping the Santa Cruz Mid-County Groundwater Basin. If formalized, the agreement could allow that aquifer to refill naturally, and armor against sea water infiltrating underground water supply. That would theoretically also boost the City’s drinking water supply, in the long-term.
The water sharing pilot program was first approved in 2016, but drought conditions limited longer-term data collection, according to Santa Cruz Water Director Rosemary Menard.
“We need to understand more about how this works, about how the aquifer responds, one season of trying isn’t enough,” Menard said.
So far, water district staff have only been able to test the pilot program for one full wet season. The extension would authorize the water suppliers to gather data for an additional five winter seasons.
To get surface water to Soquel Creek customer’s taps it requires mixing groundwater and surface water sources. That intermingling can impact water quality.
Groundwater sources in general, containers higher levels of dissolved minerals, like calcium, or iron, compared to surface water, Menard said. Those drinking water surfaces above ground, also have higher levels of oxygen. When intermixed, chemical reactions between the two types of water, can impact things such as drinking water color.
“The 2018 to 2019 winter tests did demonstrate that there was not an issue, water quality parameters were measured carefully, we didn’t see anything that was a concern, but more years of evaluation are better than a single cycle,” Menard said.
The pilot program is just one
strategy of many to try and boost Santa Cruz County’s water supply. It will take more than one option to combat shorter and more sporadic wet seasons, the water director said.
“This water — it’s quantity-limited — there’s not an endless supply of it, it’s not available in some years, like this one or last year, while it will be quite available in other years,” Menard said.
On the upside, because the water sharing program would utilize existing water infrastructure, it’s relatively low cost, compared to other options, Menard said.
If the amended pilot program is passed by City Council members, Soquel Creek Water would pay $1,930 per million gallons transferred. As it is now, water staff projected an average of 115 million gallons could be transferred from the City to Soquel Creek during November through April.
“If it can be used as part of a longer-term strategy, then that’s good, but I’m pretty sure that the amount we have available, is not reliably available, and it won’t solve everybody’s problem,” Menard said. “The system, especially with the climate change impact, is seeing more dry years, more wet years, fewer normal years.”