evaporation rates, runoff and groundwater recharge occurs mainly during winter. Precipitation and vegetation were different in New Mexico during the ice ages, when Lake Estancia existed. From numerous proxy data (vegetation changes, rodent middens and glacier changes) it appears that during the Last Glacial Maximum (LGM) summers were colder than today, with less or no cooling during winter. During the LGM, precipitation may have increased around and south of the latitude of Lake Estancia, while it decreased north of it. As temperatures decreased by the snowline of the Manzano Mountains decreased by and river flow increased. An interplay between climatic patterns such as the North American Monsoon and the El Nino-Southern Oscillation, the effects of solar cycles and variations of the Laurentide Ice Sheet controlled the climate of the Southwestern United States during the Pleistocene and Holocene. Lake Estancia is only one among several lakes in New Mexico that formed or expanded during the ice ages. During the LGM, tropical lakes had shrunk but water levels in lakes of Southwestern North America and Northern Africa rose. Rising water levels in Southwestern North America – including Lake Estancia – have been variously attributed either to increased precipitation from storm track changes induced by continental glaciation or to decreased evaporation. The exact timing of the highstands of Lake Estancia – during the LGM or during a warmer wetter period after the LGM – has also been debated. Biota The fossil animal fauna at Lake Estancia is represented by Rancholabrean species. Fossils include ducks, the large horse Equus occidentalis and tiger salamander. There were mammoths at the lake, either after it dried up or during the "Lake Willard" stage. Based on pollen data, sagebrush grassland occurred around Lake Estancia, with pine-spruce woodland in the Manzano Mountains. Increased water availability probably allowed grazing animals to thrive around the lake. Various fossils have been found in lake deposits, including algae, diatoms, foraminifera, gastropods, ostracods and pelecypods. During desiccation phases, mollusks disappeared and charophyte, ditch grass, Ruppia and stonewort grew in the wet soils and saltwater. Vegetation around the lake may have consisted of open parkland. Fossils of cutthroat trout have been found in deposits left by Lake Estancia; it appears to be the only fish species that lived in the lake. It probably was most closely related either to cutthroat trout from the Pecos River east of the Estancia Valley or to an extinct middle