Since the general plan affects the welfare of current and future generations, state law requires that the plan take a long-term perspective (§65300 GovCode). The general plan projects conditions and needs into the future as a basis for determining objectives. It also establishes long-term policy for day-to-day decision-making based upon those objectives.

The time frames for effective planning vary among issues. The housing element, for example, specifically involves time increments of five years. Geologic hazards, on the other hand, persist for hundreds or thousands of years. Sewer, water, and road systems are generally designed with a 30- to 50-year lifespan. Capital improvement planning is typically based upon a five or seven-year term. Economic trends may change rapidly in response to outside forces.

Differences in time frame also affect the formulation of general plan goals, objectives, policies, and implementation measures. Goals and objectives are longer term, slowly evolving to suit changing community values or to reflect the success of action programs. Specific policies tend to be shorter term, shifting with the political climate or self-imposed time limits. Implementation programs tend to have the shortest span because they must quickly respond to the demands of new funding sources, the results of their own activities, and the jurisdiction’s immediate needs and problems.

Most jurisdictions select 15 to 20 years as the long-term horizon for the general plan. The horizon does not mark an end point, but rather provides a general context in which to make shorter-term decisions. The local jurisdiction may choose a time horizon that serves its particular needs.

Remember that planning is a continuous process; the general plan should be reviewed regularly, regardless of its horizon, and revised as new information becomes available and as community needs and values change. For instance, new population projections that indicate that housing will be needed at a greater clip than anticipated, an unexpected major development in a neighboring jurisdiction that greatly increases traffic congestion, or a ballot initiative that establishes an urban growth boundary may all trigger the need to revise the general plan. A general plan based upon outdated information and projections is not a sound basis for day-to-day decision-making and may be legally inadequate. As such, it will be susceptible to successful legal challenge.