San Ramon's population surged between 2000 and 2010, growing 61 percent from 44,722 people to 72,148 people, according to a report delivered to City Council Tuesday night.
The information, based on the 2010 Census, was presented in a report by Assistant Planer Ryan Driscoll.
"The city started at just over 23,000 when it was incorporated in 1983," Driscoll said.
The 1990 Census showed the city's population at a little over 35,000.
It's probably no surprise that the majority of population growth since 2000 occurred in Dougherty Valley. As of 2010, an estimated 26,445 people called the area home.
The median age in San Ramon has increased too. In 2000, the median age was 36.5 years old, and went to 37.1 years old in 2010, which is in line with the national trend, due in part to the growth in population over 65.
From 2000 and 2010, the city's population aged 65 and older has more than doubled from 2,709 people -- 6 percent -- to 5,627 people -- 8 percent.
Along with that, San Ramon has seen a jump in the number of young people.
In 2000 26.3 percent of San Ramon's population, approximately 11,762 people, were under 18 years old. By 2010, the population under 18 years old grew by 81 percent to 21,351 people or 30 percent.
Dougherty Valley paints a different picture than the rest of San Ramon. While that area has a significant number of children 0 to 14 and adults between 30 and 50 years old, The Dougherty Valley has fewer older people, those above 65, and young adults aged 20 to 30.
Household sizes have increased in San Ramon, with about 2.85 people per household in 2010, up from 2.64 in 2000, Driscoll told the Council. Dougherty Valley's population per household was 3.32.
"There's a large number of young children and a large number of people between 30 and 50," Driscoll said.
That increase, and the increase in Dougherty Valley in particular, is troublesome to Council members.
"The low grades are going to flow through the system and cause a great disruption in classroom sizes," said Scott Perkins.
"This is not something that's going to go away," added Councilman Dave Hudson. "This is not we just fix this little thing and it's gone. We need to plan and be prepared for an influx of 5,400 kids in Dougherty Valley and that's what we're dong now."
Additionally, there are more multigenerational families, those with three or more generations in a single household. That increase is also centered largely in the Dougherty Valley.
There's been a large increase in the Asian population, which has climbed from 15 percent to 36 percent, while the percentage of white people living in the city has dropped from 77 percent to 64 percent, with increases in African American and Hispanics.
Data on household income is not yet available from the Census Bureau.
It's a snapshot in time, in 2010, actually," Driscoll said. "We just pulled out a few things to present to City Council."