Parents are bracing for another round of redistricting that could affect hundreds of students and every high school in Howard, as school officials prepare for the opening of the county's 12th high school.

In fast-growing Howard, redistricting has become a fact of life, with new schools opening almost every year. Now little more than a mound of dirt off Old Frederick Road in Marriottsville, Marriott's Ridge High School is scheduled to open next August to relieve crowding at several high schools in western Howard.

That in turn creates room for students to transfer to those schools from crowded ones in the east. The resulting ripple effect is likely to inflame passions and once again make redistricting one of the most contentious issues in the county.

"There's a certain affinity associated with those [high] schools and those friends," said David Drown, the school system's director of geographic systems, who oversees redistricting. "When you start messing with that, obviously there are emotions involved."

Marriott's Ridge will accommodate 1,332 students but will open next year with only freshmen and sophomores. As school board members did when Reservoir High opened in Fulton two years ago, they decided not to redistrict juniors and seniors because the transition for those students would be too unsettling.

Parents were scheduled to get their first look at preliminary plans for new high school and middle school boundary lines in meetings Tuesday and yesterday evenings. After hearing public comment, Drown and other school officials will present a formal plan to the board Oct. 28.

Under the first proposal, dubbed the "red plan," Marriott's Ridge would draw students from the county's three most crowded high schools: Mount Hebron, Glenelg and Centennial. It would also receive all students attending Mount View Middle School, which is across the road from Marriott's Ridge, as well as some students from Burleigh Manor.

Of the high schools, Mount Hebron would send the most students, about 500, followed by Glenelg with about 400 and Centennial with about 150, Drown said in an interview Monday. The moves would create space that would be filled by students from other schools.

For example, several hundred students from River Hill would go to Glenelg, where county officials are close to approving a long-awaited addition to accommodate 400 more students by 2007. Atholton and Reservoir high schools then would send some of their students to River Hill.

Meanwhile, school officials also are trying to alleviate crowding at Howard High by moving about 120 students to Long Reach High School. Long Reach's student body is projected to drop by about 400 as the county phases out technology magnet classes and a regional program of English for Speakers of Other Languages.

Meanwhile, Oakland Mills High School is dealing with a different kind of problem: It has too few students. Under the "red plan," it would receive students from Hammond High School who live in the neighborhoods of McGills North and Hopewell. And finally, about 40 students who live near the Mall of Columbia and would attend Wilde Lake High School, instead would go to Atholton.

The second proposal, dubbed the "green plan," is less aggressive, Drown said, leaving Reservoir, Atholton and Wilde Lake untouched. Under that plan, however, several schools would remain crowded whereas others would end up with small student enrollments. River Hill, for example, would be only about 91 percent full and Glenelg about 84 percent.

Under the "green plan," Marriott's Ridge would draw the same number of students from Centennial and Mount Hebron as it does under the "red plan" but fewer from Glenelg. It would also receive about 250 to 300 students from the northern section of River Hill's district.

The ripple continues from east to west: Centennial would get students from Howard who live in Wheatfield, along with two neighborhoods off Route 40 that are now districted for Mount Hebron. Half of the students who live in Green Bridge and attend Centennial would go to Glenelg.

The move from Howard to Long Reach is the same under the "green plan." Oakland Mills would also receive students from Hammond, although the affected neighborhoods would be different.

In addition, school officials want to help relieve crowding at Patapsco Middle School by shifting about 70 children from there to Burleigh Manor. Other moves involve shifting students from Hammond Middle to Oakland Mills Middle and from Patuxent Valley Middle to Cradlerock School.

Drown said that the final plan for school boundary lines will likely be a combination of the red and green plans and will incorporate parent feedback.

"We will draw upon these [plans] as our blueprint," he said.

In 2001, before Reservoir opened, school officials revamped the redistricting process to include more community input. Some parents believed their children were being sent to a lower-performing school, and others simply did not want them to move. Some students had transferred schools three or more times in just a few years.

Now, parents want to see stability and a plan that could remain largely intact for at least five years, said PTA Council President Deborah Wessner.

"We're hoping that there is a substantial duration that these new boundaries, especially for the high schools, will hold," she said.