Almost one quarter of Lake County's population now lives in poverty, the U.S. Census Bureau said Tuesday.

According to the bureau's annual American Community Survey, the share of Lake County residents who have fallen below the federal poverty level rose from 17.4 percent in 2006 to 24.6 percent in 2009.

Even more dramatic, the survey found that the number of married couples living in poverty in Lake County has soared from 3.8 percent in 2006 to 14.2 percent in 2009.

Lake County now ranks second in overall poverty among the 40 California counties with populations greater than 65,000 people. Merced County ranked first with 25.4 percent of its residents in poverty.

In 2006, it Lake County ranked 12th.

The survey illustrates the devastating impact the recession has had on North Coast communities.

In Sonoma County, for example, the number of households on food stamps went from 4,641 in 2006 to 7,215 in 2009. In contrast, the median household income in Sonoma County, $62,368 in 2009, did not change much from what it was in 2006.

County officials said the actual number of households that received food stamps in 2009 is larger than what the Census Bureau has estimated, possibly because the federal government has a different definition of household.

Marion Deeds, director of the economic assistance division of Sonoma County Human Services, said at least 11,000 households received food stamps from July to December of 2009. What both federal and local data show is that the number of food stamp recipients is increasing.

"In 2009, their incomes might have dropped to the point where they qualified for the program," Deeds said.

Lake County administrator Kelly Cox could not be reached for comment Tuesday.

Melissa Fulton, CEO of the Lake County Chamber of Commerce, said she could not comment on the Census Bureau's poverty findings because she hadn't yet reviewed the data. Fulton said she didn't have much faith in the Census Bureau, having worked on the local 2010 Census committee.

However, Fulton admitted that the recession has battered Lake County's economy.

"Obviously we have a high unemployment rate and our small businesses are having a hard time of it," she said. "We are no different than Santa Rosa, San Francisco, any other community."

Sonoma and Mendocino counties experienced no significant change in the number of people living in poverty. In Sonoma County, 9.3 percent of residents were below the poverty line last year, while 17.3 percent of Mendocino County residents were in poverty, the Census Bureau reported.

The federal government's poverty threshold depends on the number of people in a family. The weighted average poverty threshold for a family of four in 2009 was $21,954; for a family of three it was $17,098.

Among the survey's other findings:

-- In 2009, there were 73,310 foreign-born residents in Sonoma County, a decrease of 9,531 people since 2006.

-- The share of Sonoma County's population that speaks Spanish at home remained statistically the same between 2006 and 2009. The Census Bureau reported that 17.7 percent of the county's residents 5 or older spoke Spanish at home last year.

-- The number of Sonoma County residents with graduate or professional degrees comprised 12.1 percent of the population 25 years and older in 2009, up from 10 percent in 2006. In 2009, there were 39,000 people in this category.

-- More people are renting in Sonoma County. The Census Bureau reported that 60.7 percent of the county's 180,378 housing units were occupied by their owners, down from 63.9 percent in 2006.

-- In Mendocino County, the percent of those 25 and older with an associates degree rose from 8.6 percent in 2006 to 12.1 percent in 2009.

-- The share of Mendocino workers 16 and over who said they drove to work alone increased from 66.3 percent in 2006 to 73.2 percent in 2009.

Many of the survey's findings for the period between 2006 and 2009 described an economic scenario that has become all too familiar.

For example, in Sonoma County the percentage of people 16 and older working in construction jobs decreased from 10.8 percent in 2006 to 8.6 percent in 2009. The share of sales and office jobs decreased from 28.7 percent in 2006 to 23.4 percent in 2009.

Under industry-specific categories, the share of retail jobs held by those 16 and older working fell from 14.3 percent in 2006 to 12.2 percent in 2009. Meanwhile, the share of workers in education, health care and social assistance services increased from 18 percent to 21.7 percent during that same period.

Robert Eyler, chairman of the economics department at Sonoma State University, said the big jump in the health and human service category was likely due to an increase in health care jobs.

The American Community Survey results released Tuesday is the first volley of a series of data the Census Bureau will issue in the coming months. The survey is based on responses collected in 2009.

The Census Bureau said the first set of 2010 Census data, including the nation's population and state congressional apportionment figures, will be released by the end of 2010.

News Researchers Teresa Meikle and Janet Balicki contributed to this story.