Wednesday, September 21, 2011

Owens Lake in California

Owens Lake in California

This astronaut photograph highlights the mostly dry bed of Owens Lake, located in theOwens River Valley between the Inyo Mountains and the Sierra Nevada. Shallow groundwater, springs, and seeps support minor wetlands and a central brine pool. Two bright red areas along the margins of the brine pool indicate the presence of halophilic (salt-loving) organisms known as archaeans. Gray and white materials within the lake bed are exposed sediments and salt crusts. The nearby towns of Olancha and Lone Pine are marked by the presence of green vegetation, indicating a more constant availability of water.

The present-day Owens Lake was once part of a much larger lake and river system along the northeastern border of California and Nevada during the Pleistocene Epoch (about 3 million to 12,000 years ago). Melt water from alpine glaciers in the Sierra Nevada filled the regional valleys of the Basin and Range to form glacial lakes—ancestors of the now-dry lakebeds (or playas) of Owens, Searles Lake, and China Lake.

While Searles and China Lakes dried out because of regional changes to a hotter and drier climate, Owens Lake became desiccated largely due to the diversion of the Owens River in the early 20th century to serve the needs of Los Angeles, 266 kilometers (165 miles) to the south. Following complete desiccation of the lakebed in 1926, significant amounts of windblown dust were produced. Residents of the now largely abandoned town of Keeler (on the eastern side of the lake) coined the term “Keeler fog” to describe the airborne dust.

In addition to adverse health effects on local residents, dust from Owens Lake has been linked to reductions of visibility in nearby national parks, forests, and wilderness areas. Recently, the City of Los Angeles has undertaken efforts to control dust evolution from the lakebed.

No comments: