SAN RAMON -- Defying their old reputation as simple bedroom communities, Contra Costa County and the Tri-Valley area have become job centers where more than half the residents work locally, according to a new study.
About 56 percent of the workforce living in Contra Costa County and the Tri-Valley have jobs in those areas, Beacon Economics researchers reported Wednesday in a study for a group of Contra Costa business and government leaders.
The Tri-Valley includes a two-county area stretching from Alamo to Livermore in the San Ramon, Livermore and Amador valleys.
To be sure, many people from the two areas commute out of the East Bay -- about 24 percent -- particularly the affluent, highly educated people who are traveling to high-paying legal and financial jobs in San Francisco and high-tech jobs in Santa Clara County.
"But the idea that the East Bay is simply a 'bedroom' community or a community for lower skilled workers who can't afford housing in San Francisco is completely wrong," the researchers reported. "While the East Bay is a net exporter of jobs, the region is still an important work center."
Beacon researchers examined census data to do the commute pattern study for the Contra Costa Economic Partnership, a coalition of business, education and government leaders.
While Contra Costa County remained the favorite workplace for Contra Costa residents, their next most popular job site was Alameda County. Some 19.8 percent of Contra Costa residents worked in Alameda County in 2012, while 14.6 percent worked in San Francisco, and 2.8 percent worked in Santa Clara County.
Among Tri-Valley residents, some 11.5 percent of residents commuted to jobs in San Francisco County and 8 percent commuted to Santa Clara County.
Higher-income, higher-educated workers are the most likely to commute to jobs in other areas, said Chris Thornberg, a Beacon economist and founding partner.
"It took me aback that the higher-skilled workers are doing the commuting on a daily basis," he said. "The lower skilled you are, the likelier you are to live close to work."
Higher-income workers choose to live far from their high-paying jobs because they prefer good schools, parks, homes with large yards, open spaces and the environment in areas like the Tri-Valley and Contra Costa County, Thornberg added.
Commuting causes traffic congestion, smog and greenhouse gases, Thornberg said, but the affluent workers' spending on their homes at local stores and businesses pumps dollars into Contra Costa and the Tri-Valley. "It's a boost to the local economy," he said.
The supply of highly skilled workers also can be an asset in attracting new businesses to Contra Costa and the Tri-Valley, he added.
In the long run, though, Thornberg said it's desirable to have enough local jobs to reduce commuting.
In a panel discussion Wednesday after the study was presented to the East Bay Leadership Council, top managers from Contra Costa and Alameda congestion management agencies said the area needs to invest in a mix of transportation options to meet the needs of diverse commuters.
"One size doesn't fit all," said Randy Iwasaki, executive director of the Contra Costa Transportation Authority.
Art Dao, the Alameda County Transportation Commission chief executive, said the two counties need to continue to working closely together on carpool lanes, toll lanes and other projects on freeways through both counties.
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.