Summer Lake is a large, shallow, alkali lake in Lake County, Oregon, United States located 5mi south of the small, unincorporated community of Summer Lake, Oregon. At high water it is about 15mi long and 5mi wide, and supports a wide variety of birds and other wildlife in its marshes. The lake was named by explorer John C. Fremont on his expedition into Central Oregon in 1843.Ancient Lake ChewaucanThe arid lands around Summer Lake were once lush. During the Pleistocene Epoch, vast areas of this region of south central Oregon were covered by lakes and wetlands. As the last ice age was ending, rain and runoff from melting snow filled the lowlands throughout this region of the Great Basin, creating an immense, freshwater lake called Lake Chewaucan. The lake covered 461sqmi at depths of up to 375ft.Lake Chewaucan covered the Summer Lake basin and drainage system much of the late Pleistocene. The last high water period is thought to have occurred about 13,000 years ago. There is archaeological evidence of human use of Lake Chewaucan during this time. The oldest known human remains in the Western Hemisphere come from the Paisley Caves, wave-cut caves currently 10 miles southwest from Summer Lake. Lake Chewaucan began to dry up at the close of the Pleistocene. As it shrank, salts and alkali were concentrated in its remaining waters. The exposed lake bottom sediments were blown by the prevailing westerly winds to form the sand dunes that still lie on the east side of Summer Lake.
