Summer Lake, Oregon: A Haven for Birds

Summer Lake Stats

Geography and Hydrography

When Summer Lake is full, it has a length of 24 kilometers (15 miles) and a maximum width of 8 kilometers (5 miles), covering a surface area of 102 square kilometers (39 square miles). It sits at an altitude of 1,265 meters (4,151 feet), in an enclosed fault-block basin.

Water levels in the lake fluctuate dramatically, and during the summer season Summer Lake is almost dry. The main inflow into the lake is Ana River, which is spring-fed. Small snow-fed streams that rise on the adjacent Winter Ridge also flow into the lake. Because the lake is endorheic, it doesn’t have any outflows.

Due to the impoundment of Ana River, the flow of water to the lake has been reduced since 1923. Combined with the increased use of water for irrigation, this has led to the decrease of the average water level in the lake. The state of the lake’s water is distinctly hypereutrophic.

Except the nearby Winter Ridge which is covered with timber, most of the lake’s basin is arid and only supports desert vegetation.

Geology

Even though nowadays the lands around Summer Lake are arid, this was not always the case. In the Pleistocene, vast areas in south and central Oregon were lush, covered by lakes and wetlands. When the last ice age was ending, melting snow filled the lowlands and created a large freshwater lake name Lake Chewaucan, which used to cover an area of 1,190 square kilometers (461 square miles), and reached depths of 114 meters (375 feet). Summer Lake and Abert Lake, which is 32 kilometers (20 miles) away, are the only remnants of Lake Chewaucan.

Lake Chewaucan covered the current basin of Summer Lake for much of the late Pleistocene, with the last high water period occurring 13,000 years ago. As Lake Chewaucan started drying up at the end of the Pleistocene, salts and alkali remained concentrated in its shrinking waters. The sediments from the bottom of the lake were blown by the westerly winds, forming the sand dunes that lie at the east of Summer Lake.

History

Humans began occupying the Summer Lake area 11,000 years ago, as evidenced by the Paisley Caves, which were excavated by Luther Cressman in the late 1930s.

Captain John C. Frémont spotted and named the lake in 1843, during his mapping expedition in central Oregon. Frémont’s and his team were mapping the Oregon Territory from Columbia River to Sutter's Fort in California. On December 16th, 1843, the party was struggling to reach the large lake from a snow-covered plateau down a steep cliff. Frémont described Summer Lake as a "beautiful lake, some twenty miles in length". Because of the great contrast between the ridge the party was sitting on and the lake, Frémont named the mountain Winter Ridge and the lake Summer Lake.

Ecology

Summer Lake is a habitat for a wide variety of birds and other wildlife. More than 250 species of birds can be found here, including bald eagles, white faced ibis, Canada geese, goshawks, yellow-headed blackbirds, red-tail hawks, hermit thrushes, many species of ducks, and great blue herons. Summer Lake is a popular bird watching area.

Summer Lake Wildlife Area is located on the northern side of the lake. Established in 1944, it covers an area of 77 square kilometers (30 square miles), and is administered by the Oregon Department of Fish and Wildlife. It is a popular destination for wildlife viewing and environmental education, due to its abundance of wildlife and geographic setting.

The area is an important stop for waterfowl that travel along the Pacific Flyway during the spring and fall migrations. The Summer Lake Wildlife Area also provides habitat for a wide variety of mammals, as well as several species of fish. The water for the wetlands in the refuge is supplied by the Ana River.

The headquarters of the refuge is located along Oregon Route 31 in Summer Lake town. A tour route, 13.4 kilometers (8.3 miles) in length, is open to the public for most of the year, except during hunting season which lasts from early October through late January. The best time to visit is between March and May, for viewing migrating flocks of waterfowl including plumaged ducks, swans, and geese.