Take Home Message

The basin can easily accomodate a 2.8 population growth rate, with land use planning having significant role in determining were that growth will occur.

Key Findings

Urban planning areas

  • The basin has a large capacity within the existing land base and zoning to easily accomodate anticipated population growth.
  • Management plays a significant role in determining the allocation of new population growth between urban and agricultural areas.
  • The largest change in land cover occurs in the Ag. Boom Less Managed (ABLM) scenario.  This scenario expands agricultural land into shrubland areas leading to increased water demand for crop production.

Background

Population is assumed to grow at the same rate for all scenarios presented here. A sustained 2.8 percent annual growth rate to the end of the study period (2070) was assumed, based on historic growth rates over the last two decades. We note, however, that there has been wide year to year fluctuations in these rates, which we do not consider in these results.

The first set of charts below report results for the developed areas in the basin, depicted in the map to the right. The left hand chart shows the percent of development that occurs inside an Urban Growth Area for each of the scenarios. In the more managed scenarios, most new population growth occurs in the existing Urban Growth Areas due to restrictions on new development outside of these areas. In the less managed scenarios, these rules are relaxed and as a consequence more development occurs in rural lands.

The right hand chart shows the portion of new growth that occurs in the Wood River Valley. Under the more managed scenarios, the bulk of new growth is in this area, while under the less managed scenarios, most new growth occurs in the rural areas.

 

Portion of New Growth Added Within ALL Urban Growth Areas

In the more managed scenarios, most new population growth occurs in the existing Urban Growth Areas due to restrictions on new development outside of these areas. In the less managed scenarios, these rules are relaxed and as a consequence more development occurs in rural lands.

Portion of New Growth Added in WRV Urban Growth Area

Under the more managed scenarios, the bulk of new growth is in the Wood River Valley, while under the less managed scenarios, most new growth occurs in the rural areas.

 

Land Available for New Growth

The capacity to accomodate new growth is presented next. The capacity is calculated by comparing the existing population density at any point in time, and comparing that to the density allowed by the existing zoning, if any. The rules governing changes in zoning varied by scenario, with the more managed scenarios generally providing more restrictive zoning and increased allowed densities, while the less managed scenarios generally relaxing zoning constraints. In the chart below, the results from the four management scenarios are presented as a percentage of available development capacity through the study period.

 

Land Use Change

Change in Agricultural Area Change in Shrubland Area