DAVIS (CBS SF) — A new forecast says the economic impact of California’s drought will grow by $500 million in 2015, to $2.7 billion.

The study released Tuesday by the University of California at Davis includes a one-third increase in the number of acres that farmers are fallowing for lack of water. The total is now 564,000 acres.

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The study says the drought, now in its fourth year, will be worse for state farmers this year in terms of reduced water availability and economic impact to agriculture.

California is the country’s leading state in terms of agricultural production.

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Researchers say that even with increased groundwater pumping, state farmers in 2015 will run 2.5 million acre-feet short of the water they normally use.

However, the study says overall increases in crop prices are expected to remain modest in 2015, at less than 2 percent.

An acre-foot of water is enough to supply one to two households for a year.

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