Water Supply Showcase Floats Solutions

Recycled water and temporary groundwater storage were among the attention-getting ideas at the Water Supply Showcase, hosted by the Santa Cruz Water Department.

by Traci Hukill

Sept. 11, 2015—If the recent (now hopefully waning) heat wave hasn't put the fear of the water gods in the 90,000 customers of the Santa Cruz Water Department, not much will. So it's handy that the Department-sponsored Water Supply Showcase took place on Wednesday evening, Sept. 9, smack in the middle of a week of 90-plus-degree weather.

Wednesday was our chance to see what the Water Supply Advisory Committee (WSAC) has been working on since its formation in April 2014. This group of citizens, tasked with finding ways to increase the city's baseline water supply in preparation for worse/more frequent droughts and tougher regulations on diverting water from fish habitat, had to work within some basic constraints. One, almost all (95%) of the city's water comes from annual rainfall, which can't be controlled, in the form of river and stream flows. Two, manufacturing more water—as in desalinating seawater—is politically problematic.

That leaves, basically, conservation and storage as the options when the WSAC makes its presentation to the Santa Cruz City Council later this fall. And maybe one other thing ... but we'll get to that.

In case you missed it, here's a rundown of the Seven Stations of the Water Supply Showcase that were up in Louden Nelson Auditorium on Sept. 9, each staffed by a committee member or two to provide details. An estimated 150 people cruised the stations, talking with WSAC members and taking it all in.

1. Water Supply Problem Statement
This is where they laid the scope of the problem on us. "The projected worst-year-gap between peak-season available supply and demand in a worst drought year is about 1.2 billion gallons," said a handout available at the table. (That's 1200 million gallons.) The statement says storage is to blame: "Santa Cruz's water supply reliability issue is the result of having only a marginally adequate amount of storage to serve demand during dry and critically dry years..." (our italics). Right now storage is limited to the Loch Lomond reservoir. Storage will be a theme here.

2. Santa Cruz Water Supply Convention
This is where the results of an October 2014 ideafest with the public were listed—stuff like condensation harvesting, plastic-powered desalination and reservoirs in old quarries. View the Santa Cruz Water Supply Convention ideas list here.

3. Conservation
A few folks circled around this station, which had handouts about the amount of water that can be saved from specific conservation measures. For example, large-scale laundry water reuse could save 1.4 million gallons per year per 100 occupied rooms in the city. High-efficiency clothes washers could save 48 million gallons per year.

4. Water Exchange
The first storage proposal, also known as "In-Lieu Recharge." This would mean selling Santa Cruz's excess winter water to Soquel Creek Water District, which would use that water for their customers instead of water pumped from their overdrawn Purisima aquifer. At some point in the future, when the Purisima aquifer was healthier, Santa Cruz would buy water from Soquel Creek. A trade could also be arranged with Scotts Valley. This would require some additional infrastructure.

5. Aquifer Storage and Recovery
The second storage proposal. Extra winter rainfall would be "injected into aquifers through new and existing wells ... allowing the aquifers to recharge." After the aquifers were healthy, Santa Cruz Water Department could pump out the water and use it for customers. In the meantime it could pump out in the summertime an amount equal to what it had pumped in during winter. This would require modifying wells so that water could run through them both ways.

6. Recycled Water
This is a variation on so-called toilet-to-tap, used in some form in Orange County, the International Space Station and Wichita Falls, Tex. Wastewater is treated to advanced standards, then mixed with ordinary surface water from the San Lorenzo River or North Coast streams. Next it is re-treated at the Graham Hill water treatment facility, then piped to homes and business. A significantly more costly variation would pump treated wastewater into the aquifers first for a period of rest or seasoning or whatever you want to call it, but that would require new wells, as agencies can't legally pump wastewater into the same spot in an aquifer where they are pumping out groundwater.

7. Desalination
It's still here, although the two committee members seemed a little like Maytag repairmen at their none-too-busy station.

I asked WSAC member Mark Mesiti-Miller about costs. Estimates are tough, he cautioned, but he said this: "Recycled water is $85 million; it's the cheapest. Desalination is $150 million. In-lieu recharge would run $170 million. Aquifer storage $200 million.

"Which one would you rather have?" he asked.

Read A Water Supply for The Future.