The 2011 Prairie Dog Habitat Suitablity Model was developed by the Rainwater Basin Joint Venture using an additive ranking method of six variables based on expert opinion: soil range site, soil psammency, depth to water table, slope, land cover, and wetlands/hydrology. Many variables in the 2011 model are based on a previous 2004 Nebraska Game and Parks Commission (NGPC) Model developed by GIS Workshop in 2003.