Increasing salinity is not the only dilemma at the Salton Sea. The Salton Sea is a polluted body of water. Elevated levels of selenium and DDE (a breakdown product of DDT, the chlorine based pesticide banned in the United States in 1972, but still in use in Mexico) were detected in the fish and waterfowl at the Salton Sea National Wildlife Refuge. There are reports that the Salton Sea is also polluted by untreated sewage. The source of this sewage is said to be the New and Alamo Rivers (which also bring in Mexican agricultural run-off). This water flows across the International Border from Mexico, into the Salton Sea. These river do bring much needed fresh water, helping to decrease the salinity, to the Salton Sea.

The Salton Sea is also major stopping over point for migratory birds. Bird watchers are also a major part of the tourist trade that supports the area. Endangered species of birds found at the Salton Sea include the Peregrine Falcon and Yuma clapper rail.

Selenium concentrations exceeding the criteria for the protection of aquatic life were found in irrigation drainages that feed into the Salton Sea. In people, selenium can cause growth and development problems for the young, and nerve, sexual, skin and stomach problems for adults. Certain environmental protection groups warn pregnant woman and children not to eat fish caught in the Salton Sea. They also warning adults not to exceed 8 ounces of fish a month, due to the elevated selenium levels. Studies show that elevated levels of selenium also cause reproductive failure and stunted growth in bird chicks. Selenium can undermine a bird's immune system and its resistance to common bird diseases. The Salton Sea is well known for its periodic die-offs of birds such as grebes and pelicans. Every year there are major die-offs (up to 150,000 birds at a time) of migratory birds. DDE, the breakdown product of DDT has both been detected in the Salton Sea. DDT was outlawed in the United States when it was discovered to thin the shells of bird eggs, causing them to be crushed when brooded. DDT is still in use in Mexico, and birds usually do not recognize political boundaries.

This is shuttle image STS039-0094-0009. The International Border with Mexico is easily identified. Can you find the border? Look at the above "Mexico" link to check if you are correct.

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