The Snowmastodon site, also known as the Ziegler Reservoir fossil site, is the location of an important Ice Age fossil excavation near Snowmass Village, Colorado. Fossils were first discovered on October 14, 2010, during the construction of a 5 hectare reservoir to supply Snowmass Village with water. Over the subsequent weeks, after an agreement had been reached to allow paleontological excavation, crews from the Denver Museum of Nature & Science and the U.S. Geological Survey worked along with the construction crews as more fossil material was uncovered. The site closed for five months over the winter, reopening May 15, 2011. Between May 15 and July 4, 2011, crews from the Denver Museum of Nature & Science conducted a large scale fossil excavation alongside construction crews building a dam for the reservoir. In total over 36,000 vertebrate fossils (including mammoths, mastodons, ground sloths, horses, camels and deer), more than 100 species of fossil invertebrates and over 100 species of fossil plants were found in sediments deposited by an alpine lake during the last interglacial period. Discovery The fossil site was discovered on October 14, 2010, by Gould Construction Inc. crews who had been employed by the Snowmass Water and Sanitation District (SWSD) to expand the Ziegler Reservoir and provide additional water supplies to the nearby town of Snowmass Village. While clearing the perimeter of the reservoir, bulldozer operator Jesse Steele unearthed the first animal bones. Recognizing them as possible fossils, Steele informed project foreman, Kent Olson. Olsen took the bones home and identified them as belonging to a mammoth using sources he found on the internet. The next morning, Kit Hamby, the district manager for the Snowmass Water and Sanitation District (SWSD), contacted a contractor from the Colorado Geological Survey who contacted the Denver Museum of Nature & Science (DMNS). The DMNS reached an agreement with the SWSD to allow the museum to excavate the fossils. Crews from the Denver Museum, U.S. Geological Survey, and several other institutions work alongside bulldozers for two weeks in order to salvage the increasing number of fossils being unearthed. The onset of winter caused the site to be closed for five months beginning November 15. When the excavation resumed on May 15, 2011, museum crews had 7 weeks to complete the excavation in order for the reservoir project to be completed on time. By the time excavation had been completed, the team consisting of more