SANTA CRUZ -- The city's Water Commission heard updated supply-and-demand projections Monday that officials say still demonstrate a strong need for a proposed desalination plant.
The city's Integrated Water Plan, passed in 2005 to pursue a new water supply, conserve and cut use by 15 percent during dry years is outdated, water officials said. It predicted an annual demand of 5.3 billion gallons, but didn't take into account conservation measures and economic factors that have significantly reduced demand and environmental measures that threaten supply.
The Water Department now forecasts demand at 3.5 billion gallons in the next couple of years and 3.8 billion gallons by 2030 for a system capable of producing 4.3 billion gallons in normal years. The city expects use this year to end at 3.3 billion gallons.
But supply will be cut sharply in future years to meet demands by fisheries regulators, who want the city to reduce its diversions on the San Lorenzo River and North Coast streams to improve habitat for endangered and threatened species.
"The margin of error in estimating conservation savings is de minimus compared to the amount of water we are losing to the environment," Deputy Water Director Linette Almond said.
If regulators accept the city's plan to provide 80 percent of natural flow in wet and normal years and less than that in dry and critically dry years, the city can keep curtailment to 15 percent with a desalination facility producing up to 2.5 million gallons per day and nearly doubling the capacity by 2030.
But if regulators insist on the 80 percent flow standard in every year, the city can't meet future demand even if the desalination facility produced up to 4.5 million gallons per day, officials said. The department said the city would have to consider an even larger plant, pursue a different water supply project or increase curtailment in dry years.
The environmental analysis for the desalination proposal is expected in March.
On Monday, the commission recommended the City Council approve a contract with Maddaus Water Management, a Contra Costa County firm, for a yearlong Water Conservation Master Plan. The nearly $200,000 contract will update the city's overall conservation plan that ended in 2010.
"We are going to cast a very wide net, as wide a net as possible," conservation manager Toby Goddard said. "There is going to be an elimination process, but we start off with the broadest possible menu so we don't leave off any innovative measures."
The plan will be integrated with a separate baseline study expected in early 2013 that will identify how much conservation may still be possible using energy-efficient retrofits and other existing programs.
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