This dataset represents the prevalence of tamarisk (tamarisk penalty) as mapped along the Colorado River bottomland from the Colorado state line (San Juan and Grand Counties, Utah) to the southern Canyonlands NP boundary, as of September 2010. Traditional image interpretation cues were used to develop the polygons, such as shape, size, pattern, tone, texture, color, and shadow, from high resolution, true color, aerial imagery (0.3m resolution), acquired for the project. Additional, public available aerial photos (NAIP, 2011) were used to cross-reference cover classes. As with any digital layer, this layer is a representation of what is actually occurring on the ground. Errors are inherent in any interpretation of ground qualities. Due to the "snapshot" nature of the aerial photos, this cover layer reflects conditions that existed when the imagery was collected (September, 2010). This mapping was conducted as part of the Colorado River Conservation Planning Project, a joint effort between the National Park Service, The Nature Conservancy, US Geological Survey, Bureau of Land Management, and Utah Forestry Fire and State Lands.