Desal Valley

Gary Petersen, general manager of the Salinas Valley Basin Groundwater Sustainability Agency, is weighing what to do next as he concludes his work shepherding through the groundwater sustainability plan.

On par with mission architecture or cattle ranching is another consequential relic of Spanish colonialism in California: the idea that water pumped from underground belongs to whoever owns the land above.

In the Central Valley, a major danger of unregulated pumping has been a drooping of the surface at a rate of one foot a year. Here, in the Salinas Valley, so much freshwater has been extracted that, in some aquifers, the natural flow from continent to ocean has reversed – seawater is pushing through gravel and sand into groundwater sources, threatening to spoil a critical household and agricultural supply.

Now, the Sustainable Groundwater Management Act is forcing an end to endless pumping in the state’s most overpumped areas. By Jan. 31, the GSA’s of the Salinas Valley and elsewhere must submit long-term plans to save their freshwater aquifers.

The plan approved by the board of the Salinas Valley GSA on Jan. 9 features a slew of solutions like eradicating thirsty reeds invading the watershed, and proposed pumping limits that could lead to the fallowing of some farmland.

Also envisioned are a “wall” against seawater and possibly a new desalination plant that would dwarf the project being pursued by the Monterey Peninsula’s water utility, California American Water. The plan lists as one of its priorities the construction of a string of 18 pumps reaching hundreds of feet underground at an estimated cost of about $102 million. They would be drilled along an 8.5-mile stretch of land between Marina and Castroville, where the Salinas Valley Basin meets the ocean. The pumps would extract brackish water and form a barrier against the further intrusion of seawater.

Tens of thousands of acre-feet of water would have to be removed each year for the barrier to be effective – so comes the question of what to do with this massive flow. It could be conveyed and discharged into the Pacific Ocean. “Alternatively,” the plan says, “the extracted water or a portion thereof could be conveyed to a new or existing desalination facility where it can be treated for potable and/or agricultural use.”

Three desalination plants have been proposed for the region including the one that Cal Am wants to build near Marina in order to meet the water demands of the Monterey Peninsula. Cal Am has long planned to supply its plant with wells built on an industrial site on the city’s beach. But the city of Marina has resisted playing host to the wells and forced Cal Am to challenge the city at the California Coastal Commission. Cal Am’s chances of prevailing dropped afterCommission staff sided with Marina in November, urging commissioners to vote against the plant; a hearing is set for March in Scotts Valley.

Cautioning that its numbers are “a very rough estimate,” the Salinas Valley GSA has estimated what it would cost to build its own desal plant: $182 million.

The plant would produce 15,000 acre-feet of water per year, which is more than the Peninsula needs, at a cost of $2,440 per acre-feet per year, which is far less than what Cal Am estimates its own desalinated water would cost.

Asaf Shalev is a staff writer at the Monterey County Weekly. He covers the environment, agriculture and K-12 education, as well as Seaside, Marina, Sand City, Big Sur and Carmel Valley.

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