Stinson considers desalination plant

10/12/2017

Stinson Beach County Water District is considering a small desalination unit both as a way to meet peak demand during the town’s busy tourist season and to prepare for reduced flow in future periods of drought. 

The desalination committee’s two members and other district employees met last week to discuss the next steps, which include outreach to the California Coastal Commission as a “temperature gauge” on the idea and to a third-party contractor for a price estimate for a feasibility study. 

“We aren’t going for a massive structure,” Jim Zell, a board director and member of the desalination committee, said. “It’s important to note that this is small scale.” 

The district’s average daily use is 80 gallons a minute, but General Manager Ed Schmidt said that number more than doubles during summer months, and even during weekends with a heavy influx of tourists. (Currently, the district pulls water from Easkoot, Fitz Henry and Black Rock Creeks.) 

“Usually, our tanks would get low during the weekends and then fill back up during the week, but during this last drought period, we had trouble filling them up,” Sandra Cross, one of the five board directors for the district who also sits on the desalination committee, said at last week’s meeting. “With climate change causing drought areas to move north, we started thinking about the huge body of water that is right at our doorstep.” 

Attendees agreed that the desalination unit should be on the smaller end, perhaps with the capacity to produce 50 to 100 gallons of water a minute, daily. Mr. Zell said the unit could be small enough to fit “inside a shed.” 

Board members also agreed that the environmental permitting both to take water out of the ocean—which lies within the Greater Farallones National Marine Sanctuary—and to dispose of the waste was daunting. 

They also expressed interest in conducting some of the feasibility study in-house, such as a plume dispersal study that would reveal the impact of releasing the brackish waste from the unit into the ocean. 

There was also hope that a smaller system would face less regulatory hurdles. Including the unit as part of a sea-level rise mitigation strategy, board members said, could increase the project’s appeal. 

Desalination units are widely used by the military for short-term emergency supply as well as for supplemental supply for drought-stricken and disaster areas. They use a variety of different chemical treatments to filter out the salt and purify water. 

Jennifer Blackman, general manager for the Bolinas Community Public Utility District, attended last week’s meeting out of curiosity. “The BCPUD board has historically been lukewarm on the topic of desalination units because of the likely heavy energy requirement in the process of squeezing salt out of ocean water,” she said. But her district “remains open and curious” to the evaluation process at Stinson. 

Bolinas has an average of approximately 60 gallons of water a minute daily and around 100 gallons at peak times.