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Chapter 9: Reliability Through Diversification
save money because they didn’t have to
build new seawater intake and discharge
infrastructure.
However, a desalination project would not
move
forward overnight. Nearly a decade of environ-
mental reviews, legal challenges and exploring
alternative project concepts would occur before
the region was ready to move ahead with this
element of the diversification plan. By 2012,
the region’s residents were committed to the
concept:
More than 80 percent of respondents
to an opinion poll said seawater desalination is
i
mportant to the region’s water supply reliability,
and more than two-thirds of them said they
would be willing to pay more in their water bills
each month to add desalination to the region’s
water supply portfolio.
9
DESALINATI
ON METHODS
Distillation involves heating water until it evaporates, leaving the salts and other minerals behind.
Collection of the evaporated water provides fresh water.
Membrane filtration techniques, such as reverse osmosis, involve pushing saltwater under
pressure through a membrane that allows water molecules to pass through, but not the larger
molecules of salts and other minerals. In effect, it
mechanically separates H
2
O from the mole-
cules that are dissolved or suspended in it. The Carslbad Desalination Project will rely on the
reverse-osmosis treatment.
The vision for “water from the West”
took a major step toward reality in
November 2012, when the Water
Authority’s Board of
Directors approved
a 30-year
Water Purchase Agreement
with Poseidon Resources for the com-
pany to build and operate a seawater
desalination plant on the shores of
Agua Hedionda Lagoon in the city of
Carlsbad. The $1 billion project
includes a facility designed to produce
up to 50 million gallons a day of
potable water, along with a 10-mile, 54-inch
diameter pipeline to deliver the supplies to San
Marcos, where it connects with the Water
Authority’s regional
water delivery system. The
Water Authority will have the option to buy the
plant for $1 at the end of the agreement period.
Public meetings for providing input on the proposed Water Purchase
Agreement in 2012 drew large crowds