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Bay Area residents have seen their incomes drop an average of 12 percent since the recession began — while incomes fell 6 percent on average on across the nation.

That disturbing finding is just one of many in a report released Wednesday by the Public Policy Institute of California. In the last three years, PPIC said, incomes in the state have declined across the economic spectrum, with lower-income families seeing the steepest losses.

The gap between upper- and lower-income families in California is now wider than ever, while the number of families in the middle-income range continues to shrink, said Sarah Bonh, a research fellow at PPIC.

"The share of families in the middle-income bucket is shrinking as globalization, trade and technological progress have hollowed out some of the job opportunities in the middle- or lower-income end," she said.

The report found that everyone — even California's richest residents — lost ground in the recession, but that the poor took the biggest hit.

The wealthiest families saw their incomes drop on average by 8 percent to $226,000 from $246,000, the report found. By contrast, the state's poorest families saw their incomes drop on average by 21 percent, to just $15,000 a year.

Researchers say the collapse of the contrustruction industry is keeping the unemployment rate high even as technology, health care and other industries rebound.

The construction industry lost nearly 400,000 jobs statewide when the housing market collapsed, said Jerry Nickelsburg, a senior economist at the UCLA Anderson Forecast. It will be years before the state needs anywhere near as much residential building as it did before the crash.

"All of those folks have skills to build homes, which are not in demand today. To get back to work means they have to have skills that people want," Nickelsburg said. 

The latest Anderson Forecast, which was also released Wednesday, predicted that the state's unemployment rate will remain in double digits through 2014, even as the California economy begins to grow more quickly in the coming year.

But inside the construction industry, some are beginning to see a reason for optimism.

"Next year will be OK but not great, and that's a major turnaround," said Mike Theriault, secretary-treasurer of the San Francisco Building and Construction Trades Council.

"It's not good yet, but there are rental projects going forward, which will be really helpful, and new media stuff going up South of Market and work at General Hospital," he said.

Unemployment has already fallen below 10 percent in much of the Bay Area. New numbers released Wednesday by the U.S. Bureau of Labor Statistics showed the South Bay's unemployment rate had fallen to 9.5 percent in October, while the jobless rate in San Francisco and the East Bay had fallen to 9.1 percent. 

"If the state could get its act together and get some infrastuctare spending under way, we could bring down unemployment even in construction," said Sean Randolph, president of the Bay Area Council Economic Institute.

In the meantime, he argued, "commercial construction is about to pick up. Hospitals, highways and high-speed rail are some of the first things that you might realistically look to to see if the unemployment rate is going to go down."