Monumental Dam in February 1969, the site was completely underwater, due to the seepage of water through thick layers of gravel that had not been accounted for. However, as the site was being flooded, the excavation team laid down plastic sheeting topped with gravel in the hopes of being able to return to the dig in the future. The location of the site is still known today, and has come under some threat of erosion from the wakes of motorized vehicles on the lake. The Army Corps of Engineers considers the site to be in stable condition with a "Satisfactory" threat rating since 2004. Findings at the site The excavations at the site revealed evidence of human occupation from a period that lasted 8,000 years, and that the area was home to humans as long ago as 11,230 years ago. The people living at the site hunted game such as elk and deer using atlatls, and also hunted smaller mammals such as beavers, while they gathered mussels from the river. The excavation turned up graves, which included beads carved from shells and spear points. One grave, that of a child, held five matching knives made of stone. The excavation also turned up chalcedony and chert projectile points. Those in the upper layers were made of agate, which is not found in the area. Stone tools were found as well, such as scrapers for use in tanning hides, and mortars and pestles. In layers dated to 7,000 years ago, a large number of shells belonging to a snail of the genus Olivella were found, which would have been imported from the West Coast of the United States, away. The majority of the shells had holes drilled through them, indicating that they had adorned necklaces. In addition, one of the five known Jefferson Peace Medals was found associated with the most recent human remains at the site, evidently having been given to a local Native American leader (presumably of the Nez Perce) during the Lewis and Clark Expedition. This medal has since been returned to the Nez Perce and reburied, as per Native American Graves Protection and Repatriation Act regulations. Analyzing the pollen sequences at the site showed a steppe ecosystem immediately following the retreat of glaciers 13,000 years ago, which gave way to a mixed forest of pine and spruce, which led into the current sagebrush prairie ecosystem. Implications of the