Showing posts with label salinity. Show all posts
Showing posts with label salinity. Show all posts

Saturday, July 12, 2014

By the Sea, by the Sea, by the Salty Salton Sea

An air traveler flying east from Los Angeles International Airport flies over the smoggy urban sprawl and gradually ascends over the mountains and desert southeast of the Los Angeles Basin.  Continuing past the San Jacinto Mountains, our intrepid traveler sees to the south a broad basin with a shimmering blue lake, rimmed by mountains. This is the Salton Sea.
The basin where the Salton Sea now sits was once the northern extension of the Gulf of California. Over thousands of years, the Colorado River deposited so much sediment in its delta, it filled the basin and the Gulf retreated southwards. Native Americans occupied the basin 10,000 years ago and left archaeological remains. The Colorado River spilled over into the Salton Basin on numerous occasions over the millennia, creating intermittent lakes, one of which was Lake Cahuilla in 700 A.D.

The present lake was formed in 1901, when the California Development Company, intending to develop agricultural land, dug irrigation canals from the Colorado River. Because of heavy siltation in the canals, engineers created a cut in the western bank of the Colorado to allow more water to reach the valley. But heavy spring flood waters broke through the engineered canal and nearly all the river’s flow rushed into the valley. By the time the breach was closed, the present-day Salton Sea was formed. Historic photographs show a train being derailed by the flood, and H.B. Bell's 1911 novel, The Winning of Barbara Worth, covers this event.  The present lake is about 200 feet below sea level and covers about 380 square miles (from a May 2011 pamphlet by the US Fish & Wildlife Service).
The southern part of the sea is rimmed with dikes, most of which have a road along the top.  South of the dikes are irrigated farmlands.  In the first photograph, the factory in the distance is one of seven CalEnergy geothermal electricity plants. Water is heated by near-surface magma, and deep wells drilled in the geothermal field allow water to come to the surface and power electrical generators. CalSouthern sells the electricity to the grid. This is the same concept used by power plants in Iceland, a nation without oil or gas reserves, but with volcanism and near-surface magma.

The two photographs above were taken from Rock Hill, a volcanic plug that sticks up out of the soft sediments that make up most of the basin.  Rock Hill is in  the Sonny Bono Salton Sea National Wildlife Refuge:
"The Refuge is located within the Pacific Flyway, an important migration route for birds. The Refuge habitats and the Salton Sea are vital to these migrating birds as a resting place and wintering area. The Refuge was established as a sanctuary and breeding ground for birds and other wildlife when 32,766 acres were set aside in 1930."
The refuge was established in 1930 by a Proclamation from President Herbert Hoover. Originally, it consisted of 37,600 acres, but because of flooding by the Salton Sea, now only about 2,200 manageable acres remain (in other words, much of the refuge is under water).
This is an example of farm runoff. It is runoff from agriculture that maintains the Salton Sea, preventing it from evaporating in the hot arid climate. But, the irrigation water leaches salt out of the soil, and, over time, increases the salt content in the Salton Sea.  Currently, the salinity in the Salton Sea is about 44‰ (parts per thousand). To compare with other water bodies, the Pacific Ocean is 35‰, Utah's Great Salt Lake is 280 ‰, the Dead Sea about 210 ‰, and California's Mono Lake is 87 ‰ (from Saltonsea.ca.gov). The major ecological risk is if salinity increases too much, fish will not be able to survive, and the food source for countless migrating birds will disappear.
This is what happens to docks and concrete in contact with the water. Pilings get coated with a rind of salt, and steel is totally eaten away. These photographs were from Bombay Beach, subject of the next essay. You have never seen better urban decay until you have visited Bombay Beach.

Various web sites with scientific and ecological data:
  1. A general summary and overview of ecological problems is at this San Diego State University site.
  2. The State of California has a chronology of events at the Salton Sea
  3. The U.S. Geological Survey has a Salton Sea Science Office with publications and  LIDAR data.
  4. The US Fish & Wildlife Service has a site about the Sonny Bono Salton Sea National Wildlife Refuge.
References

Bell, H.B. 1911.  The Winning of Barbara Worth.  Kessinger Publishing LLC (2010 facsimile reprint, 518p.

The first photograph was taken by my friend, Bill Birkemeier, from InTheLens.com.  The others are with a Fuji X-E1 digital camera, with RAW files processed with PhotoNinja or DxO filmpack.