In the News

Desal is great for Saudi Arabia, but not Santa Cruz

By Scott McGilvray
Commentary, Santa Cruz Sentinel, 10/9/11

The proposed Santa Cruz desalination plant will cost $130 million to build and $3 million per year to operate before we add interest expense and inflation. The water produced by this plant will be a maximum of 900 million gallons per year. To get any water from a desalination effort, we have to spend the entire amount of money to build the plant.

There are several other means of providing additional potable water to Santa Cruz and environs that are less costly and more incremental in nature. First are the excess winter flows down the San Lorenzo River to the sea. Second is the opportunity to recycle treated effluent, which is produced at the Santa Cruz regional sewage treatment plant. Third are declining water demand and conservation.

More about the San Lorenzo River: Mr. John Ricker of the Santa Cruz County Health Services Agency has studied winter flows in the San Lorenzo River. His report demonstrates that these untapped flows averaged more than 800 million gallons per year for the past 35 years. If the pumping capacity and water rights were increased, the total available water could exceed 1.4 billion gallons per year.

More about recycling: The Santa Cruz regional sewage treatment plant, located at Neary Lagoon, treats and pumps 2.8 billion gallons per year of secondary treated effluent into the ocean off Lighthouse Point. According to the Water Reuse Foundation in a September 2011 study, treatment of secondary effluent to potable water standards requires less than 50 percent of the cost and energy of seawater desalination.

Declining water demand and conservation: While the effect of conservation efforts is unknown, it is clear that annual water demand has declined 922 million gallons in the Santa Cruz Water Department service area in the past 10 years. In the Soquel Creek Water District service area, annual water demand has declined by 664 million gallons in the past 10 years. There has been a consistent effort by all California water districts to promote water conservation over the past 10 years.

As a result of implementing conservation rate structures tiered rates, rebate programs and education of the populace, consumption per capita has dropped all over California. Los Angeles, Orange County and Santa Clara Valley have all seen declines in water use over the past 10 years. These declines statewide may indicate a new base level of urban water demand.

Additional water for fish: It appears that summer water pumping from the San Lorenzo River may be restricted to benefit fish. How much is not clear. This new unknown demand increases the need to harvest the winter flows from the river and recycle our sewage treatment effluent.

I have been involved in statewide water conservation since 1990 when I was appointed by then-Gov. George Deukmejian as a member of the task force which wrote the legislation that became the Model Water Efficient Landscape Ordinance, AB 325. My experience convinces me that there is additional water to be obtained by water transfers, expanding rebate programs, greywater recycling, and higher conservation awareness and practices.

Desalination makes sense in Saudi Arabia. It should be the last method considered in Santa Cruz County where we have substantial uncollected water to which we are already entitled. Excess winter flows and recycled water could be harvested and stored in the Soquel Creek and Scotts Valley aquifers or at a reservoir constructed at an abandoned quarry site in the county, of which we have many.

Scott McGilvray is happy to be retired and living in Santa Cruz, and is founder and president of Wateraware, a water conservation consulting business.

© 2008-2013 scwd2 Desalination Program, All rights reserved.