Time to Revise Old Assumptions

In 2003 the Santa Cruz Integrated Water Plan (IWP) was published which proposed a desalination plant. Several assumptions that led to the conclusion that we needed a plant have proven inaccurate. 2011 is the year that our elected leaders need to revise those assumptions and change course.

Assumptions to be revised include:   

1. Water demand would grow to 4.8 billion gallons by 2010
In actuality, water demand has declined since 2003, to 3.6 billion gallons in 2008, and 3.1 billion gallons in 2010. Estimates of water curtailment during a worst-case drought need to be revised accordingly.

2. The City must develop a new water supply to cope with a worst-case drought that is expected to occur rarely. The worst-case drought occurred once (1976-77) in the ninety year history of Water Department records. All other drought events would require curtailments of less than 20%, according to the IWP. There are better ways to prepare for a worst-case drought. Loch Lomond Reservoir was at 60% capacity on Oct 1 of 1975, preceding the 2-year drought. If we conserve during the dry season so that Loch Lomond remains at 85% on Oct 1 of each year, there will be more water stored in the reservoir for a second year drought than could be supplied by a desal plant. Conservative water use in the last three years has resulted in Oct 1 lake levels of 84% (2008), 90% (2009), and 90% (2010).

3. Desal is the only viable new water supply.
The 1985 North County Master Water Plan and several subsequent engineering reports all called for water exchanges between Santa Cruz and adjacent districts that are dependent on well water. Currently the County is studying the details of these exchanges, whereby Santa Cruz would supply water to Scotts Valley and Soquel Creek Districts during normal winters, and those districts could send water to Santa Cruz during drought years. Santa Cruz hesitated to pursue water exchanges, fearing the loss of water rights to restore native fish habitat. Those water rights are now being modified due to enforcement of the Endangered Species Act, removing the earlier obstacle to consideration of water exchanges.

4. Greenhouse gas emissions due to the intensive use of electricity needed to desalinate water did not merit environmental study. In its 627 pages, the 2005 Environmental Impact Report for the Integrated Water Plan makes no mention of “greenhouse gases” or “climate change”.

5. Costs of desalinated water would be affordable. The Integrated Water Plan estimated construction costs for the desal plant to be $32 million. More recent estimates range from $59 to $70 million, not counting intake or brine discharge infrastructure, water distribution pipes, or over $10 million in pre-construction studies and environmental review. According to the state PUC, cost estimates for desalinated water from a proposed plant in Monterey are $19,000 per million gallons, compared to the 2003 cost to treat a million gallons of water from Loch Lomond of $170.

6. Using a highly energy-intensive process to supply water is sustainable over the long haul. According to the Pentagon, Joint Operating Environment Report, April, 2010
“By 2012, surplus oil production capacity could entirely disappear…” The imbalance between oil supply and demand will send energy prices soaring, including natural gas and coal prices.

7. Desal technology can provide safe drinking water with a margin of error of close to zero. Frequent red tides occur in Monterey Bay, with exponential growth of algae that is difficult to monitor in a timely fashion. These algae can produce neuro-toxins that must be filtered out by the reverse osmosis membranes. Bio-fouling, bacterial accumulation on reverse osmosis filters, causes microscopic holes in the membranes . The proposed plant needs to have a fool-proof system for detecting membrane failure. Moreover, the desalination plant must exceed the performance of the pilot desal plant if unacceptable levels of tri-halomethane are to be avoided. During pilot plant testing, desalinated water mixed with City water contained levels of carcinogenic tri-halomethanes that exceeded state standards.

8. We can invest in desalination without detracting from conservation. Millions have already been spent on a pilot desal plant, environmental review and studies, and plant design. Santa Cruz lags behind other communities in replacing old toilets & appliances, replacing turf with drought-tolerant landscaping, and social marketing.

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5 Responses to Time to Revise Old Assumptions

  1. Tony Sloss says:

    I would like to know if creating an additional reservoir has been evaluated or cost effectiveness and feasibility. During the late 70s, the water dept. considered plans for a second reservoir in the SC mountains that was nixed, mainly for political reasons of limiting growth. An additional reservoir might be the most environmentally benign water source, though require overcoming some political hurdles. Though it gives less diversification of water sources, it would increase our capacity considerably.

    • RickLonginotti says:

      Hi Tony,
      Thanks for your comments. While damming a creek is no longer an option given more stringent fish habitat requirements, there are several ways to increase storage. One is using winter runoff to fill old quarries. This option is being studied by the County. Another is raising the dam height at Loch Lomond by a few feet. And probably the most promising is “storing” water in the aquifers of Soquel Creek Water District and Scotts Valley Water District by sending Santa Cruz water to those districts during months with ample runoff. Santa Cruz could receive well water from those districts during drought years. See “Regional Water Swap” in the Alternatives to Desal menu.

  2. Peter Scott says:

    I see you have an image of Oakes Hall, on the campus of the Vermont Law School in South Royalton, Vermont. Built in 1998, it features (among many green attributes) the use of composting toilets. The rule of thumb for ordinary toilets is 16 gallons per person per day, but this building uses (as your caption says) only 16 gallons for the entire building per day, for a building with around 300 occupants. More information is available at
    this link . We could emulate their example.

  3. Rich Persoff says:

    Why – (and NOT rhetorically) has SCWD not pursued the desalination of their existing 10,000 Acre-feet (about 3.5 million gallons per year) of secondary treated waste water? Under their pet desalination scheme this water, over 99% pure, now discharged to the ocean, will be wasted diluting brine from the desalination plant.

    The County can better profit selling this resource for agriculture and benefitting employment, if it was piped (with a spur for recharge of Soquel Creek W.D. aquifers) down the county’s new rail right of way to Watsonville’s now functioning waste water reuse…

    • RickLonginotti says:

      Hi Rich,
      The water agencies have produced a white paper on why processing waste water for other use is too expensive or too impractical. You can find that white paper on the scwd2 website. I do think your ideas will be re-visited in the future. -Rick

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