The Wentzville School District is serving nearly 600 more students than it did last year.

Otherwise, St. Charles County school districts have not seen dramatic enrollment increases or decreases for the 2011-12 school year.

School districts keep a close eye on enrollment because it helps determine the amount of state aid they receive. Final counts will be sent to the Missouri Department of Elementary and Secondary Education at the end of September.

Enrollment in the Fort Zumwalt School District, the county's largest with about 18,500 students, is about the same as last spring, although it may be up by 50 to 100 students, said Superintendent Bernard DuBray.

A large number of housing changes, due to such factors as foreclosures and unemployment, have occurred in the district, as some families moved in with relatives or other families, DuBray said. He said the district received at least 130 affidavits from residents requesting permission to allow children who have moved into their household to attend local schools.

The district's full-day kindergarten, now in its second year, may be drawing more kids. DuBray said about 1,300 students signed up for kindergarten this year, up from last year.

Preliminary figures indicate the Francis Howell School District has 17,244 students, down by 46 from last year. The total includes 7,536 elementary students, 3,900 middle school students and 5,678 high school students. The district's enrollment has been dropping since the 2003-04 school year, when enrollment was 18,378.

The Wentzville School District's enrollment of 13,230 is up by 599 from a year ago and more than officials anticipated. Matt Deichmann, the district's community relations director, said the number could drop a bit by the end of September because students are still enrolling or transferring out of the district. Officials expected about 500 more students in the district, which is the fastest-growing in Missouri, according to 2010 U.S. census figures.

Meanwhile, the enrollment count so far in the St. Charles School District is down to 5,046 from last year's early count of 5,128, said Superintendent Randal Charles. Charles said 1,910 elementary students were counted, down about 40 from what was anticipated.

Orchard Farm's enrollment was up by about 60 students for a total of 1,557 — a substantial increase, considering the largely rural area the district serves and the typical size of its student body, said Assistant Superintendent Tim McInnis. Much of the growth may be coming from developments such as The New Town at St. Charles in the southwestern part of the district, he said.