Pleistocene trout from the San Luis Valley in Colorado. The fish was present in the lake during its freshwater stages, when streams running from the Sandia and Manzano Mountains into Lake Estancia formed a favorable environment for spawning. Presumably, the trout entered Lake Estancia during its overflow phases and survived its low water level phases in the lake's tributaries but were eventually wiped out during Holocene drought; no present-day reports of fish in the Estancia basin are known. According to an alternative theory, the trout could have been living in former tributaries of the Estancia Valley that headed in the Sangre de Cristo Mountains; these tributaries would have been later captured by the Rio Grande and Pecos River. Anthropology and scientific importance Humans first arrived in the Estancia Basin during a period where Lake Estancia was dry, before the rebound of water levels that took place during the Younger Dryas. The last lake cycles of Lake Estancia coincide with the Folsom period of human culture in North America. Unlike the lake itself which offered no useful resources, the surrounding region and shores were likely favorable environments for human settlement; numerous points including Folsom points have been found close to the former shores and on lake terraces. The "Lucy site" and the "Martin site" are archeological sites in the Estancia Valley; both are located in spots where water was available. Long after the lake dried up, Spaniards reported that Pueblo people traded with salt from the lake basin and there were disputes between the Church and State in the 1660s about its exploitation. Research history and scientific significance Evidence of the existence of former lakes in the Estancia Valley was first reported in 1903. Drill cores in lake sediments, landforms formed on the former shoreline and outcrops have yielded evidence of the basin's history, going back to the Illinoian glaciation. The paleoclimatic record of Lake Estancia is the best-studied in New Mexico, although different conclusions about precipitation and temperature during the ice age have been drawn from it. Compared to climatic records elsewhere in the Great Basin, the paleoclimate record of Lake Estancia is remarkably well preserved and has been used to infer general climate trends in the region as its large size allowed Lake Estancia to respond to regional climate changes. It also has a higher resolution and greater length than many other paleoclimate records. In contrast, little archeological research