Enrollment Projections Methodology

  • Forecasting enrollment requires taking several factors into consideration: 

    • Current enrollment by school level
    • School capacities
    • Historic rates of enrollment increase
    • Mapping of proposed subdivisions
    • Calculating enrollment increases based on proposed subdivisions
    • Evaluation of COMPASS residential construction estimates
    • Estimation of the timeframe of new construction

    The forecasting model used for this facility plan began with current enrollment by school.  West Ada has a variety of school capacity levels, with Silver Sage being the smallest (capacity 425) and Mountain View High School being the largest (capacity 2175). 

    As a result of a uniform building design at the elementary level, many of these schools have a similar capacity of 650-700 students.  The same is true at the middle school level, where starting in the 1995 with the opening of Eagle Middle School, West Ada has continued to build the same facility to serve middle school students.  Lewis & Clark Middle, Sawtooth Middle, Heritage Middle, and Victory Middle utilize the same floor plan, which provides enough classroom space for 1,000 students. 

    At the high school level, the building designs are less uniform, but nevertheless the high school capacities are similar, with Eagle, Meridian, Mountain View, and Rocky Mountain originally designed to serve 1800 students.  Centennial High has a slightly larger capacity of 1900. 

    Projecting future enrollment utilizes approved preliminary residential plat data, census data on students per household, and considers historic enrollment increase trends.  The preliminary residential plats are mapped across the district using ArcGIS, a geodatabase software.  The individual plats are then queried to calculate the number of future residential dwellings by geographic area.  Using the 2010 U.S. census data, the number of future homes is used to calculate future enrollment by attendance area (elementary, middle, and high).  This data was incorporated into a worksheet with formulas that can then calculate future enrollment by attendance area.  

    These calculations were compared to Community Planning Association of Southwest Idaho (COMPASS) growth data and historic data.  COMPASS is an area-wide planning agency that largely forecasts for city and road planning purposes.  On a district-wide basis, the COMPASS data would predict that enrollment would increase by 1400 students, on average, per year for the next 10 years.  This, however, is 400 students above the school district’s rate of student enrollment increase.  All these students, of course, will not enroll in West Ada schools, instead electing to enroll in charter or private schools or to elect to home school.  The comparison between COMPASS and the district’s historic enrollment increase provides some confidence that calculating on average increase of 1,000 students per year is a reasonable estimate.

Calculating Future Enrollment

  • Current Enrollment + (#plats X .7 students per household) / 13 grades

    = new students per grade by geographic area

    @1,000 New Students Per Year Across All Grades

COMPASS Projections

  • COMPASS data would predict enrollment increases of 1400 students per year, on average over the next 10 years. 

    West Ada’s 20-year annual average increase is 927 students per year.  The average over the last 10 years is 665 students per year. 

    Each map graphically displays where COMPASS anticipates residential growth, starting with the period between 2016-2019 and concluding with the period ending in 2026.

Enrollment Projections

  • The approach to projecting future school needs was to apply the future student calculation methodology outlined in this document using COMPASS data on approved preliminary plats in West Ada as of April 2020. This methodology multiplies the number of homesites that have been approved for construction by the U.S. Census data (.8 school-age students per household) times the number of approved subdivision plats. 

    The analysis is presented by regions identified by elementary schools. The key areas of growth include West Ada south of I-84; the area of the district West of Meridian Road between I-84 and the western edge of the school district; Star; and Eagle. 

    The following maps and charts show the subject areas with calculations of the number of students and estimates of the number of schools that will need to be built over the next ten years as the approved housing projects are completed.