IDENTIFYING BUILDING SITES IN SUMMIT COUNTY, COLORADO: GEOGRAPHY, GEOLOGY, AND GIS

A Geographic Information System has been developed to identify future home and business sites in Summit County, Colorado, one of the fastest growing regions in the country. About 80 percent of Summit County is administered by the U.S. Forest Service and the Bureau of Land Management, with much of the remaining 20 percent already developed. The permanent population is projected to be 31,500 by 2010, an increase of 25 percent from 2000 (Colorado Department of Local Affairs Demography Section). During ski season the current population increases to more than 100,000 on peak weekends. Where will these people go?

In addition to data layers for slope, aspect, culture, and zoning, the GIS developed here includes bedrock geology, surface geology, soil types (partial), and the presence and orientation of bedrock lineaments. Lineaments channel ground water, and their presence with respect to porous and permeable surface deposits is important to siting wells for homes and businesses. Also, building is preferred on south facing slopes (S, SE, SW) because these receive the most solar energy, but development of lower priced housing and ski slopes can still occur on suitable slopes with north-facing aspects (E, W, NE, NW). In this study, growth is projected within three km buffers that surround existing roads, emergency services, and towns, yielding six km wide areas in which building is possible. Twelve areas that range from four to nine sq km (1.6 to 3.5 sq mi) have been identified in southern Summit County. All of the areas contain some Federal land, thus, an accord will have to be reached with the Federal government to accommodate anticipated growth in the county. Incidentally, the pixel size of the GIS provides information on very small parcels of land – 0.25 acre and less – which can be used to rank building sites within housing and business developments.