MARIETTA - Cobb County School District's enrollment rose by 452 students since last August, while Marietta City Schools declined by 35 students over the same period, officials say.

Cobb's enrollment this month is 106,160, up from 105,708 in August 2008, school officials said.

That 106,160 number breaks down into 47,872 elementary school students, 23,561 middle school students, 33,034 high school students, 150 HAVEN Academy (special needs) students, 42 Performance Learning Center students, 426 Kennesaw Charter students, 502 Mableton Charter students and 573 Smyrna Charter students, according to the district.

"Our enrollment is up some especially at the elementary and high school level. We are making final adjustments in personnel to accommodate the extra students. We are not surprised by our numbers, but we're cautious in our projections due to the economy and the mobility of current students," said Cobb Schools Superintendent Fred Sanderson.

Enrollment at Marietta City Schools, by contrast, decreased from 7,793 in August 2008 to 7,758 this month, according to Marietta officials.

Superintendent Dr. Emily Lembeck said, "We are still enrolling students in the third week of school and will look for this to crest following the Labor Day weekend. We anticipated a decline in enrollment this year due to a number of factors, including economic challenges, halt on Marietta redevelopment and loss of Boston Homes (federal housing project) population. However, we are prepared to adjust for the current realities and we are looking forward to some growth as the economy rebounds in the future," Lembeck said.

Sanderson said a 2007 demographic study projected a decline in Cobb's enrollment trend by 2015.

"Most of that was due to the building out of the county, aging of the population and out migration of younger adults. However, due to the state of the economy these trends/projections could change significantly," Sanderson said.

Lindsey Tippins, who served as school board chairman in 2007, said the board directed administration to hire a firm for a demographic study in 2007 to get a better idea of what the needs of the system were in preparation for the Special Purpose Local Option Sales Tax III, which voters approved in September 2008.

"They don't have a crystal ball, but they're pretty thorough in their methodology," Tippins said of the demographic firm.

When Tippins joined the board in 1997, he said there were 84,000 students. Following 1997, the system saw a steady growth of about 2,000 to 3,000 a year, but that has since tapered off, he said.