Planning Assumptions
Here's a description of the data and policy assumptions adopted by the Board of County Commissioners (BoCC). These numbers are used by the Long Range planning department to prepare the county 20 year comprehensive growth plan.
Using these assumptions, the amount of urban and rural land that will be necessary for homes and employment is calculated. An Urban Growth Boundary (UGB) line is drawn indicating the lands intended to be developed at urban density in the future.
The population growth estimate is perhaps the most important, carefully scrutinized and contested factor in determining the amount of developable land required to handle future growth. It also has the biggest impact.
Other data and policy assumptions for homes include housing density, the detached/attached housing split, persons per household, and the urban/rural split.
Data and policy assumptions for jobs include a job creation goal and employment density.
Other data and policy assumptions used to determine land requirements for homes and jobs include:
- A market (or fudge) factor to provide additional land for choice in residential, commercial and industrial land site selection;
- A redevelopment factor (based on building value);
- An underutilized lands factor;
- An infrastructure deduction (roads , parks, etc.);
- A set aside of environmentally constrained lands.
The vacant and buildable lands model is another important data assumption that is scrutinized and contested. As of this writing, the BoCC has not given staff direction on this. Until then, the calculation of the lands needed for this update will not be complete.
Many data and policy assumptions are closely related.
For example, the population growth number is divided by the residents per household. The number of households is divided by the housing density factor. That will determine the amount of additional land needed for new dwellings.
That number is further refined after considering the market factor, redevelopment percent, infrastructure and constrained land deductions.
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